The metal is not .25" thick. I wouldn't worry about it. Or splash out a few extra quid for a new down pipe.

The guys at ExhaustsUK are top people and will make the system completely to your spec, with your choice of tailpipe and how it's fitted. I have a 4.5" slash cut, but is slightly longer so that it clears the rear bumper.

Absolutely love it. Check the link in my sig to see it, and being fitted

 

Why is this a shame?
You will find that 2.5" exhausts or those referred to as 2.5" exhausts are good to well over 400 bhp.
3" exhausts or those referred to as 3" exhausts are generally 2.75" in reality and they are good to well over 600 bhp and probably even more. You need a free flowing box and a relatively straight exhaust system but the actual diameter is not a problem.

 

It just seems a shame considering I want a true complete 3" system. I have no doubt that smallers systems can make the power, heck I'm only making 370odd bhp.

My main concern was the step down and to how it could affect the car's performance and even reliabilty due to it having been mapped on a completely 3" system.

This doubt seems to have been squashed now as many have stated it would be absolutely fine. It would really only be used for track days anyway, and then back on with the Nur Spec. So in due time I will most likely go for one of the above systems without any adverse affects hopefully!

 

I've got a magnex oval backbox on mine, with a straight through 2.5 system... gets past Croft no bother (the lowest db track in the uk at the moment)

 

Hi Guys,

Just want to help with the confusion.

Firstly all tube is measured normally by O/D ( Outside Dia ) and normally in inch's, i.e 2.5" , 3" and so on.

The wall thicknesses are normally 1.5 mm / 1.2 mm.

2.75" O/D pipework ( 70 mm O/D ) is different to 3" ( 76.6 mm O/D ) pipework.

Yes our Cobra exhaust is made in 3" bore... well the Trackday friendly version. we do do others in 2.5" bore.

And the crunch.....

Not sure if this is going to throw a spanner in the works for some people.... But one of the latest tests we've done on a 08 STI. the car was measured at 285 with standard exhaust ( Should have made 300 ) and with out digging the paper work out i remember that rolling road ( Calibrated ) results showed a 2 BHP gain from a 2.5" bore to 3" bore and that is only running at under 300 BHP ?? Sorry guys.... you can see this in action in our news section www.cobrasport.com

Any questions or queries please contact me on pete@exhaustsuk.com

Thanks for the heads up jag

 

^ I'll post some pics of my double can 2.5" centre when it arrives Pete

 

You're most welcome Pete!

As you know I've used your Cobra system on mine when it was 360, 422 and now 700+ and have not had a single issue with it which simply suggests awesome quality and they work!

Jag

 

Do you have any vids JP4? Would be nice to hear what it sounds like on a high powered car

 

Here's some pictures of my 3" ExhaustsUK set up. Love it.

Will try and get a video of it for the sound later.

 

Is that the track day system?

 

Yes it is.

Depending where you live, you're more than welcome to come and have a look, hear what it sounds like etc

Actually had someone follow me into a car park recently to ask about the system as he said it sounded so good!

 

Just to add, the tail pipe looks really long in the photo on the ramps, but that's just because i used a very wide angle lens to take the shot.

ExhaustsUK will make the tail your specs, in this case, it was left a little longer to allow for any flames that may find their way out the back. Ahem.

 

Bit far for me to come and listen mate, but I've seen it in action first hand on JP4's monster at Santa Pod. It does look very nice I have to say.

 

EXCELLENT customer service as well as price. Deffo worth giving them a bell

 

The exhaust referred to above is on an 08 car with twin tail pipes. I cannot comment on that specifically as I have not done any serious work on one of these but the twin tailpipe design is for asthetic reasons and not performance. the actual exhaust design is wanting.
A well designed single tailpipe exhaust system for that car will probably show the greatest performance increase.

On both Classic and New Age cars I know from testing that changing from a 2.5" system to 2.75 or 3" system will not free up any power until somewhere beyond 422 bhp (from an actual exhaust swap and RR testing) and there is no appreciable change in back pressure between 2.75 system and 3" system at around 550 bhp. The design of the exhaust is far more important than the actual pipe diameter, certainly upto and beyond that level.
Personally I always want and advocate where financially convenient, a 3" full decat exhaust system to allow for project creep and maximum flexibility.

 

Thanks for the input Harvey. It is much appreciated.

For anyone who wants to hear JP4s car, there are two videos of his car on my youtube channel which is linked to in my signature below

 

Got to a PC now so I can post the direct links:

Me Vs JP4 at Santa Pod

JP4 Running on his own

 

Cheers Costa! Both above runs were v-power only at 1.7 bar (less than 600hp) with full weight of 1,455kg (excl. my weight!) and no launch control, so 11.1 is fairly credible.


See above links. Also this one which was run with a passenger in the car did an 11.0 on race fuel with 1,410kg (excl. my weight)! End voice is of Paul Blamire from Zen Performance. Sadly no one took my quickest of the day of 10.8!

http://s60.photobucket.com/albums/h2...t=IMG_0002.mp4