4-2-1 or 4-1

[leebo]

hey on engine rebuild i have come down to the part where i pic my exhaust but i dont know whas the performance gaines are with each one? heard one gives more torque but i dont know which one.
cheers lee

[mowgli]

back in the old days (Eighties) every body was recommending fitting 4-2-1 exhausts on 1.2 novas. it was worth a couple of hp simply by fitting a 1.3 manifold & pipe.. everything bigger already has it fitted.

keeping a bit of back pressure on an engine does give more torque, but usually this is done with the choice of backbox

[leebo]

cheers, i just bought a 4-1 so i will soon see but i was going to put on a sr or gte system so that will give me a bita back pressure

u have any recomendations as to what line to do? be it gte, sr or other cheers