it would make a HUGE difference. those things are the major setbacks for our cars. 2.5" is the best size for our cars...anything more or less is unnecessary. as far as the flowmasters, they sound great but as far as flow is concerned, they are the worst flowing mufflers on the market and sell based on their name and sound alone. if you looking for max flow which would be great for future mods, go with the hooker aerochambers, spintechs, dynomax ultraflow ss, pypes, jegs, summit, or even the borlas. for the money, dynomax, pypes, hooker, jegs, and summit are your best options. i personally have used both the dynomax (which im currently running) and the pypes violator on my 1996 impala and i love the dynomax the best because with the resonators supplied in the kit, they are super super quiet at idle like the factory ones but the flow of them is in the top three as far as all the ones i mentioned above. plus the price of the jegs catback and dynomax catback cant be beat. for cold air, i am running the K&N FIPK and its great. nice growl when you get on it. but one thing i need to tell you is that when you do upgrade to the cai and 2.5" exhaust, your car will lose low end torque because of the loss in backpressure due to the free flowing exhaust. however, it does pick back up in the top end. you will notice it in the low and the top end. it wont take off as hard as it does now but it will pull harder in the upper rpm range.Was wondering if an aftermarket exhaust system and a K&N cold air intake would make a big difference in Fuel Economy for my LT-1?
My exhaust plans was for 2.5'' straight pipes with 40 series mufflers....Would this setup increase any horsepower? Any other advise?