Exhaust Options

[optimax sniffer]

With the cerb up with Joo, I now have some requirements...

At the moment one of the cats has collapsed and is blocking flow, also one the rear sports exhaust boxes has cracked and either needs welding up or replacing...

Options:

1) New cats and weld rear box(es)
2) Decat and weld rear box(es) - Too Loud????
2) Decat & SP rear box - http://www.silverstoneperformance.co.uk/
3) Act exhaust with cherry bombs and rear silencing - http://www.actproducts.co.uk/shop/sj10c45-p-360.ht...
4) Act exhaust with cherry bombs and no rear silencing (probably too loud) - http://www.actproducts.co.uk/shop/sj10b45-p-359.ht...
5) Any other options?

Need to get on tracks, namely Spa next month.

Help !!!!

[FarmyardPants]

I would go for decat and sp, looks and sounds the bks.

[AL 123]

4) Act exhaust with cherry bombs and no rear silencing (probably too loud) - http://www.actproducts.co.uk/shop/sj10b45-p-359.ht...


Need to get on tracks, namely Spa next month.

Help !!!!
[/quote]

Option 4 sounds interesting. Would this get through MOT? & would it pop & bang like a de-cat exhaust??

Probably to loud for track days etc...

[grahamn]

ACT Cherry Bombs and SP rear box sounds really good and is still only 100-101 dbs so you can still get on track days.

[Ireland]

Don't forget that the louder the car becomes on the outside, the louder it will become on the inside.

It'll be tough going on the 4 hours or so of motorway driving from Calais to Spa and back.

I'm speaking from experience here ..... I made the mistake already.

I had the original type sports pipes on with de-cats.

I drove the length of France having to shout at my passenger to be heard at anything over 50 MPH.

I've now got de-cat with original back box and that's fine.

If you go louder than that you'll really need to line the floor with Dynamat or similar to maintain any sort of comfort for yourself.




But the SP does sound good .....

[julian64]

I'd ask joo, but personnally I'd stick with weld rear box and decats, as its NOT too loud, and will get you onto all tracks.

If I remember far enough back joo said that this option was probably power optimal, whereas some of the louder setups were actually sucking power.

Of course that could just be me hearing what I wanted to hear

[touching cloth]

Straight through decat and Sp box box here and love it, I'm around 104db. Slightly jittery at stricter circuits especially those with drive by (I've been avoiding Goodwood but really want to do it) as that's always a bit of an unknown, but get on 105 days where it's a static. Linked decat are meant to be a bit quieter still so you could do that also (that is what the full SP system uses), and Graham's Act cherry bombs cat replacement along with an SP back looks a good combo if you want to bring noise down further. Might have to investigate this myself as can then do a 105 at Goodwood without fretting.

[spitfire4v8]

another piece of info to throw in is that teh sports pipes currently fitted are the cheaper ones with the crush-bends which restrict flow, also they're 4.2 versions which have been sleeveed to fit the 4.5 intermediate pipes, so not only are they crush bends but they're starting with smaller diameter pipe as well, double horsepower-sapping whammy

[stuthemong]

I am musing this exact same point. I'm keen to remove cats due to gearbox heating and potential collapse, but am concerned about the noise level as I have sport pipes on at the moment

These decat silencer pipes
http://www.actproducts.co.uk/shop/sjd02a-p-432.htm...

Would they be the same volume as my catted sports at the moment, louder, or quieter? I *really* don't want to go louder.

those SP exhausts look the danglies, I'd *really* like one, but my money is best put elsewhere I think. You should get one though

Stu

[a1rak]

I've got the silenced decat pipes from ACT and found it difficult to tell the difference between the CATs and the silenced DECAT's.I have sports silencers on the rear. The also do track day silencers that bolt on the tail pipe...got these to and they make a substantial difference and as far as I am aware have passed most track side db levels.

[stuthemong]

Right,

I just gave ACT a call actually - their opinion was that the decat silencers are not as good as cats for supression of noise, but much better than striaght through. His opinion was that if I didn't want my system any louder, cats-> silenced decats wasn't a solution, as it would be louder.

a1rak, interesting you say that then. Maybe I should just give it a shot, as it seems no matter what I do, the silenced decats are probably what I'll want in the system, somehow.

Joo, what is your opinion on cat/decat for power/running of the engine? Does the lower back pressure harm midrange torque? etc

[TT Tim]

stuthemong said:

Right,

I just gave ACT a call actually - their opinion was that the decat silencers are not as good as cats for supression of noise, but much better than striaght through. His opinion was that if I didn't want my system any louder, cats-> silenced decats wasn't a solution, as it would be louder.

a1rak, interesting you say that then. Maybe I should just give it a shot, as it seems no matter what I do, the silenced decats are probably what I'll want in the system, somehow.

Joo, what is your opinion on cat/decat for power/running of the engine? Does the lower back pressure harm midrange torque? etc

They change the tone of he exhaust too, a decatted Cerb' seems to have a higher note than mine, which used Tim's cherry bomb decats. I have a bespoke 2.5" sports system from decats back, with repackable sports boxes, I see 105-106dB on 3/4 throttle, 99dB when the track tails are on.

Good compromise, didn't seem to sap the power either - or at least that's what it showed on Jools' rollers. :-)

Tim

[stuthemong]

For clarity, Tim's Cherry bomb decat - is this the ACT silenced decat, or something else?

There are so many options I'm reet confused

.. plus those ACT manifolds look teh sex! I know I shouldn't though...

Does anyone know where the best place to get a stock 4.2 or 4.5 backbox is & What do they tend to go for?

[amazon]

I have a 4.2 Cerbera with a 4.5 backbox, de-catted, with straight through pipes from ACT.

At 5,250 rpm sound tested at 101dB.

Still pops and bangs

[julian64]

101 seems quite for that. I'm 98 and standard back box with linked decats.

If I didn't worry about the odd track day I'd rip open the back box, whip the gubbins out and then close it back up again.

Would have a proper echoic chamber then. None of this harsh raspy pipes straight out sports stuff.

Anyone done this for real? Tis a sound I'd like to hear.

[flyingdutchie]

Just out of exhaustinterest you should look on youtube and search for aero turbine mufflers. Interesting patented technology and they will last a lifetime.

[FUBAR]

ACT 3" Big Bore sports zorst, decatted here. Its funny, and maybe Im deaf, Ive never found the noise so bad I cant talk (ok, with a raised voice) to a passenger, nor do I get a headache after prolonged motorway driving

Noise tested between 109 and 112 (oddly, one tailpipe is noisier than the other?)

Ive got the ACT TD cans (which bring the noise down to 98), but the car is at Austec as I type having a mod done so that I can swap the complete tails over with the TD cans so they stay within the bodywork.

[JensenA]

Another option is to travel up to Leeds (or find someone similar nearer to you) and get a custom made exhaust. Tony has had a look at my SP Exhaust system, and can make up a similar full system for under £600. He will make it sound how you want it to sound. I've seen his work, it's good, he knows what he is doing - he's done systems for new Astons, Ferraris and Lambos - well worth a trip up.

http://www.tonybanks.co.uk/

Edited by JensenA on Tuesday 8th September 17:05

[Byker28i]

Sp exhaust sounds good but the rear box is as large as the original and heavy. On my car decatted it was 109db, 101db with the cats in. It's quite large so sits very low to the ground. On Grahams car it seems very low but he seems to scrapes over the speed bumps ok.

I've got the ACT quiet system (option 3), decatted it's 106db, 96db with the trackday cans. It's half the weight of the SP back box and a fraction of the size at the rear so the car can sit a little lower.
For reference, my original sports exhaust system was 106db catted, 116db decatted. That was seriously loud. I wanted decatted to cut the heat down transferred through the gearbox/clutch/cabin.

I guess we'll find out how it runs on Joo's rollers in Oct.

[VPower]

Byker28i said:

Sp exhaust sounds good but the rear box is as large as the original and heavy. On my car decatted it was 109db, 101db with the cats in. It's quite large so sits very low to the ground. On Grahams car it seems very low but he seems to scrapes over the speed bumps ok.

I've got the ACT quiet system (option 3), decatted it's 106db, 96db with the trackday cans. It's half the weight of the SP back box and a fraction of the size at the rear so the car can sit a little lower.
For reference, my original sports exhaust system was 106db catted, 116db decatted. That was seriously loud. I wanted decatted to cut the heat down transferred through the gearbox/clutch/cabin.

I guess we'll find out how it runs on Joo's rollers in Oct.

Hi, I have same as you the ACT (SJ10) system and decatted.

Can I ask at what revs you/they (race tracks) test at?

I'm doing 102bd at 4000 revs.
But it sounds so nice!

Although it has developed a rattle when hot and the welded plate holding the centre section together has snapped at the weld.

Steve