A year and a half ago, I got the 3" cat back sys. from JC for 129.00 now I see they uped the price to 249.00! Ouch!! Don't know who makes it but I felt the difference right away. Throtle responce was better and the power went up enough I could feel it. Last weekend, I removed the collar from the inside of my air cleaner and recieved an increse in the top-end (3000 to 4500). these two mods have made the most difference of all. Go to the junk yard and get a smaller air cleaner lid ( one that fits over the filter element only) and get some more. I also removed the cover plate on my offset cowl scoop to help with under hood temps. 88 Formula Lo3 TBI 700R-4 stock!