The EX is a 1.6 not a 1.8. That year SI didn't come in a 4 door and is only a manual. The SI makes 160hp and the ex makes about 127hp. The Si has tighter suspension and a limited slip differential. The civic type r is a 185hp more aggressive version of the Si. Type s is for acuras. Mugen is a company that makes parts for hondas. In order of speed by acceleration (slowest to fastest): civic si(b16a2) , civic type-r, integra type-r(b18c5), rsx type-s(k20a2). They are all get great gas mileage but of course the faster they get usually the less mileage they achieve.