Which 325 are you asking about? The E30 is a decent choice but as has been stated, it is probably just decent. The E36 in ITS is still a front runner and in ITR it should be a front runner. To say it's an underdog is a bit premature - it will have tons of power and be one of the lightest cars.

I have always wondered about the 2002 in ITB. I love the cars but common perception is that they are outclassed - yet in poskets (like the MARRS series), there are tons of them and they run up front.

How much power can a 2002 put to the ground in IT-legal trim?
[/b]
It may be premature to say the E36 is an underdog in ITR, granted we won't know for sure until some of the other possibilities are fully developed. But here's some acceleration data to show my point. This graph shows a virtual drag race between six ITR cars. The data comes from actual vehicle parameters and real dyno results (scaled to ITAC estimates). I won't divulge which car is which, other than the E36 325i/is as the slowest.

To keep this relevant to the 320 crowd, I'll throw in a diff ratio model. This plot shows the relative acceleration time at Road Atlanta for a later 320i with 100hp at the wheels. Lower time (vertical axis), indicates the better the diff ratio (horizontal axis) for that track.

As for the 2002 engine, my '77 320 had 130hp at the crank with what was supposed to be a professional build. I suspect you could do slightly better, but then the 2002 has to use a carburetor. Don't forget the suspension is archaic in those cars. The 320 and 2002 were good ITB cars before IT became so competitive. With the new models in recent years, they're outdated, and outclassed.