Best bang for buck improvement for light track use is probably 930 rear torsion bars, make sure bushings and shocks are good, track alignment and corner balance plus 7/8x16s with R-compounds. You would need race pads and some cool air ducting to keep the pedal firm for more than a few laps but then you have a car that driven well can hang with 964s, Boxster S etc. Not much other than GT3s will come past you in a hurry.
Two words of warning on the exhaust. First its too loud for most track day noise limits, so you have to sort that issue - a 2-in 1-out may just be ok. Second you need to budget for the SW chip or remapping to get the best from the exhaust. I think 245hp is acheivable if you budget on a couple of dyno runs - one to get the AFRs to send to SW and the other to test the new chip. The next step is cams. If you do 964 cams without doing the top-end you might get 250hp+ for a very reasonable price. I think 3.8 Supercup cams warrant the protection of valve springs and Ti retainers (plus rod-bolts if you can) - which starts to get expensive - because they love the revs, but you could just drop them in.
While I love my engine (and its not right yet - pulled apart again next week!) and don't regret spending the money for what is to most intents and purposes a new, bulletproof, 7,000+rpm motor, I think taking weight from the car makes a more dramatic difference than 15 or 20 hp. You really notice the lack of weight in the way the car picks up from 3000-4000rpm which is where the 3.2s are weak(ish) and where you find yourself all too often with the relatively long std gears.
Just my $0.02 - happy to discuss offline some time.
RB
RB