Originally Posted by gabrieldy
hi flow cats shouldn't void your warranty but I'm not so sure they'll pass emissions in every state. don't know what the smog laws are in OK.
totally agree with that statement.
With the stock muffler any gains you'd get by going to a high flow cat (not really needed unless you plan on camming the engine and opening up the heads a bit) or a better Y-pipe will be negligible and defeat the purpose of installing those parts.
The aftermarket mufflers will improve flow and the longer they are, the quieter they tend to be if you are worried about noise.