Good to know i was right
bro if you are into modifying ur car to get more performance, then certainly u shud go for free flow exhaust.and yes i think you will have to change the muffler too,to make unrestricted air flow. u can buy a quite exhaust if u dont want noisy ones
theres one thing which i wud point out here, by adding free flow exhaust, ur car will actually become SLOWER at below 3000RPMs, but will give enough blow after that...
i drove a stage 1 modified city idsi, had CIA,plus and free flow.it was slower until i hit 3000rpms and then was much faster... now i wud say if u drive ur car on daily basis, u wont like this, but if u are into racing etc, you ll love it