Deffinetly run a 3 inch if your doing any kind of forced induction go witht he 3 inch if your staying N/a stay in the 2.5. if you want a drag car just use the downpipe. If you run the down pipe though you run risk of back fires and very loud noise inside the cabbin. cause its right undernieth you.

 

You can either buy a muffler with 3 inlet and outlets and have a shop do custom piping for you or you could get a Thermal exhaust.

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`96 Civic B18C5 Turbo
`91 Nissan pickup

 

SR20DET Ive heard this can be a problem with the Sis. Check out www.ClubSi.com if you havent already. There was a string on it a few days ago... some people out in CA blowing the ECUs.

- Yosho

96 200SX SE-R
00 Civic Si (in about a week)