hey i need help! im looking around to get a new exhaust for my 05 mini cooper s. i already have alta v 2.0 and alta v 2.0 15% pulley now i need an exhaust. i was looking at the invidia 3" exhaust and the alta 2.5" exhaust but i dont know which is better. what size is best for the mini? and if you have anyother suggestions on exhaust please post it thank you