STI 2006 - To tune or not to tune, that's the question?

STI 2006 - To tune or not to tune, that's the question?

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theog87

Original Poster:

147 posts

74 months

Thursday 4th February 2021
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Evening chaps,

As mentioned in another post, I've just got my hands on a 2006 WRX STI with 77k on the clock.

Initially I'm going to take it to my local Scuby Indy (East Kent Subaru) to have a general look over it. I had a Click Mechanic pre purchase inspection and it did well bar the back brake pads needing changing, so will obviously do that. I will say the brakes too feel a little spongy in comparison to my older e46 M3. That might be a characteristic, or might require a recondition of kinds. I'm open to either really, but pretty sure the guy in East Kent Subaru will figure that out.

The first change I want to make is to change the standard head unit to a Android Auto double din. This will then have a cable going into the glove box for my phone so i can run google maps / contacts etc. I may even get a reverse camera, but not 100% sure where the camera will sit yet. thoughts welcome! In terms of android auto, I like the Sony XAV-AX3005DB (~£300 ex cables and install).

Tyres seem in good condition and service history seems alright, but nothing has been done in terms of pressure testing the cylinders. I say that as if I know a lot, but I really don't, but from common sense point of view (turbo / these cars generally getting ragged) I would think it would be a good thing to get checked regardless... on that note, is this quite a specialist thing to get checked, or would my local Indy be able to do this? If more specialist, what price would this be at roughly?

I believe one of the cats is already gone from the car, other than that it's stock.

Regarding tuning, I'm really in two minds... here's my thoughts so far:

Pros of NOT tuning
- Keeping value on the car... I'm the kind of guy who generally gets the car checked out quite a lot, so it will probably be in a better condition when / if I hand it over in X years time
- It's already a fantastic car, so why bother
- I'm primarily a family guy, so don't really need it. Save money and use that to take it over to Europe once ban lifts.
- Insurance stays the same
- Less chance of blowing up things

Pros of tuning
- I have only ever remapped a Seat Ibiza TDI (from 130bhp to ~160bhp), other than that, I haven't really tuned anything or modded performance wise. Might be nice for a change! The performance bump in the Seat was great, so something similar might be nice, especially if it doesn't kill the MPG but not toooo much (not that fussed really, but not looking at <10mpg on average).
- IF I do mod, I will keep the original parts and put back if / when I feel like it. When I bought my E46 M3 it had an after market exhaust. Great for a holiday, not great for every day. I kinda like the idea of having something special for a few months of the year and then switching over. Admittedly, changing an exhaust is ~£100 in labour, so much less than say a turbo or likes of.
- Part of me is interested in a twin scroll turbo to balance out the power a bit, perhaps going for something a little more than normal, but i guess this will cause problems with other elements and may not be worth it until I have forged components? That being said, I have heard the JDM twin scrolls dont sound as good?
- Forged - part of me likes the idea of this, just for peace of mind, regardless of power output. But I have no idea what this looks like cost wise. But the main thing here is confidence that IF i did put anything beyond stock, then this element is already sorted. Also I guess I can remap to a more 'sensible' bhp or go more crazy depending on what I feel is manageable.
- From speaking with East Kent Subaru, he said he will need to look at the puppy, but roughly speaking an air filter change, new fuel system and good remap could bring it to ~350bhp (not sure if this is wheel horse power though!?). Either way, I'm guessing that isn't too drastic in cost, and might provide a similar bump to my old Seat. I also understand anything beyond 350bhp gets sketchy on other elements of the engine? This is just based on american Youtube stuff (based in the UK btw).


In addition to the above, I love the various non exhaust sounds the car makes. I guess it's the subtle winning of various elements and generally solid clunks and the likes of that make it sound so good. I'm guessing it sounds slightly agricultural, or like a toned down rally car, but either way it's very nice! Only slight downside is the somewhat loud road noise, but that could be tyre related.

Part of me loves the idea of mods enhancing the general engines sounds, sounding more like a rally car. To be frank, the burble is nice (nothing on an e46 m3) but the other noises I find just as pleasing, so perhaps it could be a mod also for the sound!? That being said, it will need to go down a motorway without sounding trashy.

I know there are loads of articles out there, but I'm worried something from say 2011 may have been good on a car of that age, but I'm worried how the car will fair with the age it is now!?

Thoughts welcome, and thanks for everyone's feedback so far, really impressed!

Best

T

Not a Diesel

70 posts

215 months

Thursday 4th February 2021
quotequote all
Might be worth saying if its 2.0 Blob or a 2.5 Hawkeye.

As I think his was a transition year.

You will get some differing opinions depending on which based on the underlying engine reliability.


I am running a standard 2.0 UK Blob with the PPP.

theog87

Original Poster:

147 posts

74 months

Thursday 4th February 2021
quotequote all
Not a Diesel said:
Might be worth saying if its 2.0 Blob or a 2.5 Hawkeye.

As I think his was a transition year.

You will get some differing opinions depending on which based on the underlying engine reliability.


I am running a standard 2.0 UK Blob with the PPP.
Good shout

2.5L single turbo Hawkeye (on a 56 plate)

vxr2010

2,562 posts

159 months

Thursday 4th February 2021
quotequote all
a long read so hopefully i answer all your questions , if a cat as in centre cat deleted it won’t need a map , if the main down pipe cat or the up pipe cat is deleted then it should have been re mapped, if it’s not been mapped or at least map checked it’s not good for the car , a sensible map makes a lot of performance difference plus if you drive it sensibly after a good map has been done then mpg will improve , your engine being the 2.5 i think the worst of the fajitas was 07 onwards , a map would be worth doing as the theory was the original subaru map was as issue as it was running lean , if the cars running well is there any point doing a compression check , if i did want to get a compression test done i would go to a good subaru garage , if you are mapping change the fuel pump you can do a sports cat which helps flow and power can be a few £ , if you go to a good subaru mapper it does not mean you need to max the bhp just find a sensible power level , the torque increase will be considerable

plenty

4,680 posts

186 months

Thursday 4th February 2021
quotequote all
Decat and map it, assuming you know a friendly MoT tester. It will offer good gains and safety compared with the standard map. Although are you sure it hasn’t been mapped especially if it’s a lost a cat? Most of them have been by now.

A remap won’t damage value - the 2.5 hawk is a great car but pretty low down the collectability stakes.

Any more than a remap and you’ll be in risky territory until you forge. Twin-scroll is not exactly cheap to do and you’ll end up with a car that’s hard to sell on - far more sensible to sell and buy a JDM car. You’re looking at £3-4k to forge, £2.5-3k convert to twin-scroll. Makes no sense tbh when you can still pick up a JDM car for £10k which will appreciate if you look after it.

Spongy brakes are probably pads.

Recommend you spend some time doing searches on Scoobynet - on there is the answer to every question you could conceivably think of.

vxr2010

2,562 posts

159 months

Thursday 4th February 2021
quotequote all
a good sports cat v a de cat is around 2 bhp different , to me it’s just not worth it when it comes to mots , sports cat as above helps flow reduces spool but you still can pass an mot , i personally would steer clear of buying a scooby with a decat , if it has a sports cat it would be the other way round a good point when it comes to selling a car , as above i would think some one has mapped it already especially if cats have been removed

theog87

Original Poster:

147 posts

74 months

Friday 5th February 2021
quotequote all
Morning all

So if I were to remap + filter + Exhaust adjustment + fuel pump, you think the value won't go down much?

Just had some clarification on the car decat situation - it seems the mid decat was done but not downpipe. It didn't have PPP on purchase. So initially it came with two cats. Hope this adds clarity.


plenty

4,680 posts

186 months

Friday 5th February 2021
quotequote all
(1) Almost everybody does a remap and exhaust on Imprezas - simple mods with no downside
(2) a 2.5 hawk is not a collector's model where factory standard carries a premium

theog87

Original Poster:

147 posts

74 months

Friday 5th February 2021
quotequote all
plenty said:
(1) Almost everybody does a remap and exhaust on Imprezas - simple mods with no downside
(2) a 2.5 hawk is not a collector's model where factory standard carries a premium
Ok that's reassuring to know!

Would you say there is a go to brand for parts in general? Jap speed?

plenty

4,680 posts

186 months

Friday 5th February 2021
quotequote all
theog87 said:
Would you say there is a go to brand for parts in general? Jap speed?
Not really as it varies depending on part category.

Instead, there a number of trusted retailers who have been around a long time and have a good reputation in the Subaru community. Import Car Parts for OEM parts. Roger Clark Motorsport for tuning parts and AS Performance for both.

You can still get many OEM parts new directly from Subaru dealers.

theog87

Original Poster:

147 posts

74 months

Friday 5th February 2021
quotequote all
plenty said:
theog87 said:
Would you say there is a go to brand for parts in general? Jap speed?
Not really as it varies depending on part category.

Instead, there a number of trusted retailers who have been around a long time and have a good reputation in the Subaru community. Import Car Parts for OEM parts. Roger Clark Motorsport for tuning parts and AS Performance for both.

You can still get many OEM parts new directly from Subaru dealers.
Ace thanks for the recommendations! Will have a gander later.

plenty

4,680 posts

186 months

Friday 5th February 2021
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Also check out Scoobyworld and Scoobyworx

theog87

Original Poster:

147 posts

74 months

Sunday 14th February 2021
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Thanks for all the above everyone.

I know this might be contradiction in it's own right, but as well as loving cars, I don't really want to be screwing up the environment. Carbon offsetting is something I want to be doing this year. There are various ways of doing this, but the area which interesting me is putting money into protecting various rainforests. This saves animals etc and also the trees keep the carbon and the likes of. Really not as expensive as you think.

With the above in mind, I'm still playing with the idea of modding the car, but I understand that a number of routes requires decat or the likes of. This then brings me onto the sports cats and the likes of.

Is there a general consensus on which brand / type is the most effective at cutting out carbon / nasty's, and also has high flow rate? I'm also assuming you would only need 1 sports cat, or would you require 2?

theog87

Original Poster:

147 posts

74 months

Sunday 14th February 2021
quotequote all
Ah.....hmmm..... just watched this from Engineer Explained.

Would I be right in saying that cats don't actually remove CO2? That's a bit of a game changer. Not really sure how worried I am about nitrogen etc as 99% of my driving is through the country where very few people will be breathing it in!?

https://www.youtube.com/watch?v=HADOcrcMikA

trails

3,703 posts

149 months

Tuesday 16th February 2021
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Not entirely sure you purchased the right car if you are really that bothered about the environment...but that aside your best bang for buck is to replace the turbo up pipe with a decatted pipe, replace the air filter with a K&N/Green/Cosworth/whatever filter and swap your standard down pipe with a sports cat. Then remap. Legal, safe-ish (it is a 2.5 after all biggrin) and a fair chunk quicker than standard.

The sports cat will release more stuff into the atmosphere but nowhere near as much as a full decat, but a full decat will make more power and should feel more responsive.

Best of luck smile

Not a Diesel

70 posts

215 months

Wednesday 17th February 2021
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As has been said if you are worried about CO2 you want to find the smallest engine car you can find them minimise its use through walking/cycling.

Fuel is a source of Carbon & Hydrogen. Burning it makes CO2 & H2O.

The Cat cleans up incomplete combusion & turns NOX to N2.

Ironically I bought a V8 M3 which drunk fuel and forced me into cycling to work. Now I cycle most short journeys instead of driving car on inefficient warm up cycle. Moved on from the V8 but maintained the cycling. Win for me.. Win for Environment.

Still got a Subaru....

theog87

Original Poster:

147 posts

74 months

Thursday 18th February 2021
quotequote all
OK thanks peeps

I have a Toyota IQ for my commute which is £20 a year tax, so that takes the brunt of commuting / short journeys.

Are all the sports cars roughly the same efficiency wise / power wise?

trails

3,703 posts

149 months

Friday 19th February 2021
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No...vastly different in many ways smile

Probably worth getting the pedant hat on and saying an Impreza isn't a sports car, it's a quick saloon...I think the excepted definition of a sports car is a (typically) two seat car designed from its very inception to focus on the driving experience. Maybe.

Edited by trails on Friday 19th February 23:29

theog87

Original Poster:

147 posts

74 months

Saturday 20th February 2021
quotequote all
trails said:
No...vastly different in many ways smile

Probably worth getting the pedant hat on and saying an Impreza isn't a sports car, it's a quick saloon...I think the excepted definition of a sports car is a (typically) two seat car designed from its very inception to focus on the driving experience. Maybe.

Edited by trails on Friday 19th February 23:29
Haha loools

There was a typo in my last message. Meant to say "are all sports Cats the same" e.g. I see with impreza after market sports cats, it says 200 particles or something flow.

Are some brands better than others? Is 200 like for like 200, or some just superior?

Quite like the idea that if I do mod, I use all the same brand throughout the whole car. COBB is it?

trails

3,703 posts

149 months

Saturday 20th February 2021
quotequote all
Ha biggrin

The number denotes number of cells per square inch so 200 -obviously the lower the number the greater the flow rate- should be the same across the board smile