De-Catting - all of you need to do it!!!
Discussion
Holy Crap! 
Just got my car back from Dave Batty last night which is now running ACT sports manifolds, decat Y-piece and cherrybombs along with a new MC1 cam and all the old mods. I can report that this is the best thing I have ever spent money on (since buying the car of course!). Its SO LOUD, and instead of pops and bangs, I now get a deep rumble followed by really loud snaps and bangs which sound very firework-esque and make passers by jump and run for cover along with some flames when I really give it some right foot. The sound has totally changed from the old system (just ACT Stainless cherrybomb system) and now sounds much more angry and crisp on the throttle, then like a second world war bomber on lift off with some cannonfire thrown in for fun. Still have a huge grin on my face which is starting to get painful 
Anyway just thought I'd let you all know that despite the horrors of getting it done due to siezed bolts etc, it was totally worth it and I think it should be a compulsory mod for all TVR owners. Already had lots of comments on how good it sounds and thumbs up and I only took it on a 10 minute drive in to town in the rain! Now i'm off for another drive
- Oh and Dave Batty is fantastic and you should all use him, very very thorough guy.
Just got my car back from Dave Batty last night which is now running ACT sports manifolds, decat Y-piece and cherrybombs along with a new MC1 cam and all the old mods. I can report that this is the best thing I have ever spent money on (since buying the car of course!). Its SO LOUD, and instead of pops and bangs, I now get a deep rumble followed by really loud snaps and bangs which sound very firework-esque and make passers by jump and run for cover along with some flames when I really give it some right foot. The sound has totally changed from the old system (just ACT Stainless cherrybomb system) and now sounds much more angry and crisp on the throttle, then like a second world war bomber on lift off with some cannonfire thrown in for fun. Still have a huge grin on my face which is starting to get painful Anyway just thought I'd let you all know that despite the horrors of getting it done due to siezed bolts etc, it was totally worth it and I think it should be a compulsory mod for all TVR owners. Already had lots of comments on how good it sounds and thumbs up and I only took it on a 10 minute drive in to town in the rain! Now i'm off for another drive
- Oh and Dave Batty is fantastic and you should all use him, very very thorough guy.
Well.. its a bit of a long story but I guess it was about 795+vat for the manifolds & Y-piece, then the cam kit was around £350 but I only used the lifters and cam so that was discounted a bit (not sure how much yet but around £300 I think), then I was going to put the pipes on myself but I ran into massively siezed bolts - plain bad luck - and ended up having to leave it with Dave for a week to have the heads drilled out etc which will cost around £900 I think as it involved pretty much having a top end rebuild, and all the fuelling system, exhaust etc came out so all in all it came to rather more than I was hoping.. In fact i'm now quite poor... But turn the key and all the bad thoughts go away
Edited by thenick on Thursday 10th May 12:39
MOT wise, i'm not too bothered as I can either stick in a set of bolt in cats from ACT or I can just take it to a 'friendly' MOT centre I know of... Just had it done though so its a year before I have to worry about that! You're welcome to come have a listen, i'm up in brum at the moment and will be for the next couple of weeks but I finish for summer on the 2nd June so will be back down south then depending on where you are... Smiles per mile, I really don't think there is anything better you can do... Its my daily driver and I do use the motorway a fair bit getting to and from brum, but driving up here it was fine sitting at 2 and a bit k revs; it only gets angry when you prod it!
piemanpaul said:
Andy,
So have you actually done all that - removed the main cat and pre-cats? What's ths result? How does it sound? Bang a good'un now does it? Any probs?
So have you actually done all that - removed the main cat and pre-cats? What's ths result? How does it sound? Bang a good'un now does it? Any probs?
I am doing the Y section this weekend as i have the car in bits.
With the straight thru pipes and no precats it is quite load...cruising it is reasonable and if you get the revs right you hardly notice it...put your foot down and it screams!
I have driven behind 1 chim that had the full decat and when he put his foot down it was quite painfull to the ears and i was a good 30-40 behind him...but it did sound good.
Not had any problems at all and can well recommend doing it!!!
,if you have a tester doing this for you he must be daft or no longer wants his job
frazer guest said:
Chauch said:
Just a word of warning, I got pulled over in my last car by VOSA and was extremely lucky that I still had my cat on having just had it MOTd.
This is happening quite often now as well and their powers are quite frightening...
This is happening quite often now as well and their powers are quite frightening...
so, in theary, what could they do? i would have thought they would just give you a vehicle defect form, which would then allow you 7 days to get the defects rectified?
yes i agree(but it inconveinance),but you have then got to get the car back to cat MOT standards,i can see the point of the ACT kit but not main cat removal of standard Y piece that lets face it just makes more boom and a fraction more BHP(possibly),the standard front section is never going to flow properly no matter if you take out all three cats,i would recommend the ACT kit if you keep the standard gear(just in case of roadside stop)but oh, the fault of swapping that lot over
but stuff the law just do what you wanna do with those zorsts and Or for a more MOT, law and neighbour friendly alternative, get the pre-cats removed for that extra bhp and noise, leaving the main cat in place - the car will pass its MOT as such. 
One or 2 people, I believe, replace the main cat with a section of pipe that enables that CAT to re-bolted in relatively quickly, at will, for MOT purposes.
One or 2 people, I believe, replace the main cat with a section of pipe that enables that CAT to re-bolted in relatively quickly, at will, for MOT purposes.
stackmonkey said:
Or for a more MOT, law and neighbour friendly alternative, get the pre-cats removed for that extra bhp and noise, leaving the main cat in place - the car will pass its MOT as such.
One or 2 people, I believe, replace the main cat with a section of pipe that enables that CAT to re-bolted in relatively quickly, at will, for MOT purposes.
One or 2 people, I believe, replace the main cat with a section of pipe that enables that CAT to re-bolted in relatively quickly, at will, for MOT purposes.
Wot be the difference in sound with the precats removed? Believe its good to help reduce underbonnet heat also!
Dave.
Not sure with just the precats removed, but since I decatted mine, it hasn't once stepped above 70 degrees even in 2 hours of solid traffic on the M6 where it used to sit at 90! It now drives around at 60
It is indeed cheaper to just cut out the cats from the original pipes but that will only really make it louder, as with sleeving the exhaust. The ACT system changes the diameter of the pipes to a much smaller one with a better gas flow. This in turn improves power (a tiny bit) but radically changes the sound of the car IMHO, the closest to the original sound is found at idle, and even that is a lot different; much more angry sounding and the gas flow out of the pipes is very noticable faster now - there are now two speccled black streaks behind my car park space where it shoots carbon and water out on startup - and they extend a good 8 feet from the car! The different sound is why I personally went for the ACT stuff though as I loved the sound that Wildfire's 4.0 precat Griff makes with the same setup (search for the ACT cherrybomb video on pistonheads). There is no point discussing any performance gains as I suspect they're very small indeed, it is simply a childish need for a bigger bang when I put my foot down - pointless some might argue, but its effect is very powerful and I now find it hard not to smile like a kid when I put my foot down, and even harder not to laugh out loud when I back off and it starts to snap and bang - for this reason, it is worth it even if it does cause hasstle at the next mot, if it gets that difficult i'll just get some bolt in cats to go up front now the two mini downpipes can be slid out by removing 5 flange bolts each!
It is indeed cheaper to just cut out the cats from the original pipes but that will only really make it louder, as with sleeving the exhaust. The ACT system changes the diameter of the pipes to a much smaller one with a better gas flow. This in turn improves power (a tiny bit) but radically changes the sound of the car IMHO, the closest to the original sound is found at idle, and even that is a lot different; much more angry sounding and the gas flow out of the pipes is very noticable faster now - there are now two speccled black streaks behind my car park space where it shoots carbon and water out on startup - and they extend a good 8 feet from the car! The different sound is why I personally went for the ACT stuff though as I loved the sound that Wildfire's 4.0 precat Griff makes with the same setup (search for the ACT cherrybomb video on pistonheads). There is no point discussing any performance gains as I suspect they're very small indeed, it is simply a childish need for a bigger bang when I put my foot down - pointless some might argue, but its effect is very powerful and I now find it hard not to smile like a kid when I put my foot down, and even harder not to laugh out loud when I back off and it starts to snap and bang - for this reason, it is worth it even if it does cause hasstle at the next mot, if it gets that difficult i'll just get some bolt in cats to go up front now the two mini downpipes can be slid out by removing 5 flange bolts each!
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