Will ITR manifold bolt to stock GSI Cat ?

[stanleym]

got it all fitted today - hi tech products

from headers back 2.5" piping all the way through 4" muffler

sounds crazy gettin silencer for it but power wise improvement

[yourfather]

2.25" on the stock GSR but I could be wrong. I never measured mine before I went to 2.5" but I remember someone elsewhere saying 2.25".

2.25 on the stock gsr is correct.