I read somewhere about a mod you can do to your 335 with a golf tee a while ago... What does this do exactly performance wise? If there are any benefits to this mod, how do you do it? Anyone know the step by step instructions? (pics would be nice) Thanks.:D

There are no benefits. The exhaust has a valve that closes off one side of the muffler to make it quieter at low RPM and improve turbo response (contrary to what many people things turbos respond less with unrestricted flow).

It does make it a little louder since you'll have the full exhaust active.