Larger Bore Sports Exhaust System

[Jubes]

Hi All,
I'm having a custom stainless catback sports exhaust fitted to my Cerbera Speed Six next week.

My question is will there be any worth while performance advantages to having the system made up in a slightly larger bore than standard? If so, what diameter would people recommend please?

Any advice would be much appreciated.

[DAVEY DEE]

Hi Jubes,what system you having & where from?Are you keeping your cats in,decats or sports? Can't answer your question,but would imagine there is not much to be gained just by increasing the bore from the cat back.Being nosey really. :-)

[Jubes]

Hi Davey Dee,
I'm having the system made up by a local company in Nottingham, who specialise in custom exhausts.

I've had other exhausts made up by them in the past when my friend used to own the company and have been very pleased with their work - the same people still work there since ownership change.

I'm having 3" slash cut exit pipes and I've been quoted a really good price so I'm looking forward to getting them fitted.

I'm still wondering if it's worth increasing the diameter of the exhaust, although I'm sure the gains (if any) would be minimal.

[Jubes]

Oh forgot to mention that I'm keeping the cats in place for the moment anyway.

My main reason for keeping the cats is that I can't be bothered to keep refitting them come MOT time!

Although I'm sure I've read somewhere that they may well pass the emissions test without them? Can you throw any light on the subject maybe please?

Cheers.

[DAVEY DEE]

I'm a complete muppet unfortunately regarding anything technical,despite spending many,many hours reading on here.I had the same feelings about decats & mot time.I reckon you would.prob need a combination of both luck & "friendly" mot station to get through without cats.I'm sure a lot more would fail than pass.

My twisted logic goes like this: I prob get more enjoyment from the sound of the car than the performance,I just love it.So for me it was always gonna be decats.I reckon I could get 4 yrs worth of paying someone to swap them over come mot time(I don't have access to ramp or a pit ) for the difference in price between decats & sports cats...If that makes sense?

So 4yrs of extra noise for the same money!

No doubt someone will put me right!

Any idea how the bigger bore affects the sound?

[Jubes]

I would have thought the larger bore would make very little difference to the sound.

Are you going to fit a TVR Power De-cat EPROM too? (a very useful 20 bhp and 40 ft/lbs over standard)

[DAVEY DEE]

Having an ACT system.Got the decats,& trying to sort out the rest.Trying to do a Cerbera big bore cherry bomb system for my speed 6.They do it for the ajp & other sp6 s but it would be the first " Cerbera SP6 big bore cherry bomb system"- so I'm the guinea pig if you like.The rear tails & back box is the same as the ajp system,its the middle section they've never done before.Gotta get some pics of the underneath when she goes in for some work Tuesday.

Seems like I've been waiting ages,nothing is ever simple is it.Was definitely thinking of getting a remap afterwards coz she seems a little under powered as well.Don't know where to go though.The 'biggest' name nearest to me is Power.Can't do anything yet though till the steering rack is refurbed & the gear box issues get sorted.

It's will have been quite an expensive first few months of ownership.Oh forgot...having a set of Gaz Gold Pros fitted as well.

Can't wait ...

[Jubes]

You'll have to post some pictures of your ACT system once fitted - I'll make sure that I take some of mine when she's on the ramps.

GAZ Golds, I'm really tempted by a set too. You'll have to let me know how different (hopefully much better) the ride is once fitted.

Are you going for the slammed to the floor look or keeping it standard(ish) ride height?

Edited by Jubes on Sunday 28th August 22:08

[DAVEY DEE]

Will keep it pretty standard I imagine,although I'll take all advice given.I don't have any plans to track so a fast road set up will be plenty adequate for me.Nigel Mansell I'm not.

Must admit,I find it a bit strange that companies selling exhaust systems don't put up before & after videos on their web sites.

I'll put some up after its done..I think it will sound a bit different so won't be to everyone's taste...maybe not even mine ! Lol

[RicSpeedSix]

DAVEY DEE said:

Must admit,I find it a bit strange that companies selling exhaust systems don't put up before & after videos on their web sites.

If it's any help I've just had an ACT big bore full cherry bomb system fitted to my T350 by STR8SIX. I left the cats in place because I wanted to be able to live with the noise level on long journeys and didn't want the annual hassle at MOT time.

Verdict - sounds fantastic. Less "boomy" when sat on Motorway at 2-3k in 5th etc. Not much louder than stock system until you open it up and then it really comes alive. Nice pops and bangs on the overrun now (even with cats still in) without sounding like a complete chav. It's supposed to be trackday friendly system even with the cats out but on a recent visit to Snetterton I clocked 105dB on the static test with cats in. To be fair though, they made me hold the revs at 6k for that which seemed a bit excessive.

I've got a couple of drive by videos from the Snetterton pit lane that I'll try and post to youtube so you can listen to the sound.

Only negative point for me is that the rear cans have a weld seam half way - which to me detracts from the overall finish. Again, I'll try and take a picture to show what I mean.

[DAVEY DEE]

Nice one.

[Jubes]

RicSpeedSix said:

I've got a couple of drive by videos from the Snetterton pit lane that I'll try and post to youtube so you can listen to the sound.

I'm looking forward to listening to your videos, please post up the links once you've uploaded them to youtube.

[RicSpeedSix]

Figured out how to rip the videos off facebook and put onto youtube at last:

http://www.youtube.com/user/MrPeace2make?feature=m...
http://www.youtube.com/user/MrPeace2make?feature=m...

I'll try and do a static one for you as well and take a picture of the rear cans at some point this week. Busy trying to sort stuff out for my wedding at the moment though!

[Jubes]

Thanks for that RicSpeedSix.

Well I have to say your car sounds fantastic - just the right level of noise in my opinion.

A static vid would be nice too!

[Jubes]

Forgot to mention good luck with your wedding too!

[RicSpeedSix]

Jubes said:

A static vid would be nice too!

Tried to do one yesterday but started engine from cold so couldn't really give it any beans and sound quality wasn't very good.

Will try again after I've taken the car out for a decent run.

Are you coming to TITT7? If so, you'll be able to have a listen then

Thanks re: wedding!

[Jubes]

Thanks for trying to get the static video.

I'm unfortunately unable to make TITT7, shame as it looks like it'll be a great day, especially with the impressive number of cars attending.

[DAVEY DEE]

If mine was in better shape I'd do it.Bet it would be incredible!Looking forward to next year.Went up to Jp exhaust in Macc today for them to have a look.They'll be chatting to Tim at ACT & hopefully they'll come up with a good price for the inaugural ACT big bore cherry bomb Cerb speed 6 system.It's tight under there but they've just done one for a Sag & said it sounded awesome.

You decided to do the "Best Man Run" Ric?

[MPETT]

I'm sure the tuscan S exhausts are a larger bore? I would go bigger than this as I understand back pressure in exhaust and inlet manifold is important to bhp and torque. More sound is fun, but you don't want a peaky undrivable engine.
Will these guys making the exaust be tweaking the design with the use of a rolling road? If not and you can't fund the development cost I'd stick to what is known. However if you are going to work on a system, I need a new one as am rebuilding my whole Tuscan mk1 and my exhaust silencers are damaged.

[DAVEY DEE]

Big bore in this case is only an eighth of an inch bigger than standard so should be fine.Not expecting any performance gains.