2" will fit your factory exhaust manifolds perfectly, but 2.25 will with a little modification and it flows better. I purchased my side exhausts (factory style Reproduction) from Andre Jacobs in San Antonio TX. At the time he did not have the front plastic caps or the mufflers. I think he has them now. His phone # is (830) 980-3165 email is akjamc@xxxx and his website is http://southtexasamc.tripod.com Two years ago, when I returned my gremmie to its '74 look, I purchased the front plastic pieces from American Performance Products in Cocoa, FL., their phone # is (321) 632-8299. To see how the whole system looks, check out the Album here on Barts website under the mixx. Hope this helps.............'The Mix'