Do I have to replace my cat with a down pipe/silencer or can I use the stock exhuast with the TB mod

 

yeah, you can use stock. The difference will just be less noticeable. Do you have a turbo or an N/A? It doesn't do much for an N/A.

 

N/A I'm looking for free mods to do but a lot of them seem to be for the turbo or at least work better for the turbo............I'm losing off the line to civics and accords but blow them away when I reach 3rd what gives my car doesnt have much torque but a lot of high end HP

 

i would put a gutt my cat and are your six ports working and K&n and look at some junk yards i found my glass pack there and i could beat a civic si and camaro V6

 

The exhaust and the throttle body are completely unrelated. Neither has any effect on the other.