Does any one have any dyno plots to show the different levels of torque/Bhp for different style downpipes fitted to the same exhaust.

For example with a 2.5 inch setup which style actually gives better torque: the Scoobysport (bellmouth) design or the twin dump with the seperator plate as in the Perin or Bosal designs or the HKS which has no seperate section for the waste gate gasses...eeek .

I want to get one and have done lots of research and it seems that there are lots of opinions on the different designs but not any plots to see how they actually compare with each other.

It would be interesting and very helpful.

Many thanks to all who provide guidance

 

BTTT - I'm very interested to know this as fitting a down-pipe to my WRX has not been as noticeable as i thought it was going to be.

 

What style downpipe was it and to what year car is it fitted. The pipe alone should make a noticable difference as it removes the main cat from the system

 

Cant fault the down - pipe. Its a Scoobysport 3" to 2.5" Replaces the down-pipe off my 93WRX import.

Maybe i'm just not very sensitive to the power gains! Even replaced the up-pipe at the same time. (OK old up-pipe doesnt have a cat in it).

Maybe it will be noticeable when i fully decat the exhaust within the next week or two.

I'm praying that just replacing the up-pipe and down-pipe means that the exhausts gases are leaving quickly until they hit the original exhaust?? - meaning that i'll not notice the gain until the Blitz exhaust that i have on order is fitted. We shall see!