Hi Guys,

Currently running a H&S downpipe narrowing to 2.5" then a magnex 2.5" centre section, straight through pipe and a 2.5" Afterburner backbox.

What gains would be made if I changed to a 3" system from the 2.5" downpipe, ie Nur Spec R system or the Ninja 3" or possibly the Revolution system.

Couple of questions, would you notice the difference in power, torque, turbo spool up etc. My car is currently mapped for the 2.5", is a re map required?

Any advise or previous experience with the above would be great.

PS car is a Version 5 Type RA Ltd with a lateral 2.1 stroker engine and a VF35 Turbo.


Thanks Ben

 

if the whole exhaust was 3" maybe you'd notice but if your previous 2.5 was pretty wideopen than you won't notice too much with a change to 3" because you still have a bottle neck due to the downpipe taper. I wouldn't mess with it until you get a BIG turbo and then you'd probably want the whole thing to be 3".

 

I understand your post regarding the bottleneck, although I thought nearly all down pipes narrowed to 2.5".

Anyone swapped between the 2 sizes?

 

Anyone

 

Interested in this aswell.

 

The current system you have on your car is pretty much free flowing ,by increasing the size of the bore wont add that much extra bhp/ torque to the engine.Some tuners will advise you to go for a 3 inch system depending upon how far you are going with modding your car,but most will tell you a good 2.5 inch system will see good power gains depending on the system/make purchased.

 

Andy forrest's track car has more than 450bhp and uses a 2.5" exhaust. I know another that has in excess of 500bhp with a 2.5 smelly pipe.

You don't really a 3" exhaust unless you are going for silly power

Andy

 

Thats a Fair Point.

Still would like to know on a back to back test, what the difference would be?

 

bigger top end, bit more lag

 

I would have thought less lag as it's less restrictive, am I missing something?

 

Well I have just swapped my 2.5 downpipe back to a 3 inch and can confirm this is definately the case. I prefer it, the extra lag outweighs the extra top end performace imo.