i went to autozone and spent $40. much more quiet now.

 

you may consider painting the muffler from autozone with some rustoleum spray paint, to keep the rust away.

 

Does anyone know if there is a difference in the cat back portion of the exhaust for a 99 Si compared to other models? For instance would the cat back portion of an EX fit on a Si...or is it a different exhaust? Thanks

 

EX is same as Si catback

DX, LX, CX, HX are all the same as each other but different from the EX/Si because the catalytic converter on them is integrated into the exhaust manifold, requiring a longer exhaust.
Although, the exhaust bends are exactly the same but on the EX/Si there is a catalytic converter in the spot on the DX/LX/CX/HX have straight pipe.
Also, only a few aftermarket exhausts exist for the DX, LX, CX, and HX, and they are usually the same as an EX/Si catback but come with an extra 16" pipe that fills in the gap caused by the DX/LX/CX/HX catalytic converter location.