[snskq81]

I'm currently running RA manifolds with 2.25" outlets, with a full 2.25 exhaust with crossover and the head pipes are 2.25" 90° mandrel bent.

Would there be any point/benefit to stepping up to a 2.5" exhaust like pypes kit for instance even though the manifold outlet is only 2.25"?

[nas t eh]

Going to need to know how much engine you have, or rather it depends on how much engine you have

[Formulajones]

What's your goal?
My 70RAIII setup for ps racing with stock manifolds picked up 3 tenths a 3 mph going from stock 2 1/4 exhaust to a 2 1/2 mandrel flow master transverse force II system. Another tenth and almost 2 mph when I switched that to the Pypes 2 1/2" transverse sgf70 system

[Scarebird]

I did this 2.25 to 2.5" change, cannot speak to horsepower gain but it did get MUCH louder with the same type of muffler (Dynomax).