The five-blade fan and thermal reactors are the true enemies of the 2.7. Depending upon from where your car came (especially if it was a CA. car), if you have the fan or thermals, you should replace with an 11-blade fan and the heat exchangers from a '74 or earlier 911 model. SSIs is one direction to go if you can't find the heat exchangers. Once you do this, you may as well get a nice dual-in-dual-out exhaust muffler like a Triad or B&K.
With these mods, you could have a horsepower increase of almost 20 hp., depending on the condition of your engine, which would put even the most anemic 2.7 (which had 8.0:1 compression) at about 170 hp - ten shy of the 180 hp the 3.0 engines have.
After that, stick a 7.31 r/p in your transmission, and you'll become very heady competition for 3.0 SCs and 3.2 Carreras.
