Exhaust Theory?

[Jonny81191]

Yes you can go as big as you like but you also need to factor in gas velocity. If you go too big, you'll slow the gases down. It'll more than likely cause resonant frequencies causing your ears to bleed on the motorway. Too small and you'll obviously cause a restriction. 2.5" or 2.75" would be fine. TBH I've made a 3" for a stage 2/3 and whilst the gas velocity was high and it sounded good, I'd run 2.75" if I was to make another one. Also consider the fact that 3" really doesn't fit in a 306 exhaust tunnel.