...not back pressure again! People get this confused with the pressure wave effect.
It is very confusing actually... to me anyway
First time I changed the mid and back box on my 33 I put really big ones on and straight through. The result was that I couldnt feel the car pulling me on the seat anymore but it reved higher. The car felt slower.
Appliying a silencer on the rear box made a great difference on the pulling issue.
Then you see all these race people , they change their exhaust manifolds and dyno run the car to see what they gain , loose from just the manifolds !
Then its the angles that also create a back pressure effect, especially on the 33 where if you want your exhaust to come out from where it should, you need a tight " S " at the rear.
I have tried different manifolds, mid and rear boxes, pipe diameter sizes etc on mine and I never got it just right.
...come to think of it, can someone who doesnt find this confusing tell me whats the best exhaust setup for my 33 please ? Its a 1.8 ltr with race pistons , 11.5:1 compression ratio, fast road cams and OMEX ecu !
Iain sorry to hijack