I really regret getting my old custom crush-bent cat back with a flowmaster muffler. Didn't sound that great, power gains were nothing and i ripped it off a few months later and got my RS*R. Also regret getting super-whites and a harness to handle the higher wattage, just replaced that with my stockers. Also regret replacing my broken axles with Autozone :madfawk: axles. Those break all the damn time, some were broken right when i put them in.
Also all the money i spent this summer replacing the head gasket 3 times and valve seals twice before i figured out that i needed new piston rings. Oh well, all better now