headers
 

What are the advantages/disadvantages for 85 911 row?

bump

Advantage: reduced weight, but to be honest the couple of pounds are noise level compared to the weight of a car in stock condition.

Advantage: Improved exhaust flow, but with the small amount of overlap with the stock cams, it's not going to be huge.

Disadvantage: Loss of heat.

My recommendation: Get some SSI's. The exhaust flow is significantly better then the stock 3.2 exhaust system, almost on par with tube headers. But they still maintain the car's heating system. The difference between SSI's and real headers is most likely not significant until you change the cam to something with more overlap then the stock cams -- which results in a whole new set of compromises.

what are the compromises of changing to a more agressive cam? thanks

I'm not as familiar with the newer engines, but the Motronic would probably have to be modified to make much use of the agressive cams. The 911 motor is pretty efficient from the factory, simple and/or cheap mods usually don't get you much power. To get more power you need to look at the whole thing. Intake, Cams, Compression, Ignition, Exhaust, Fuel Delivery, and the bits needed to support those changes.

and emissions - more agressive cam - less likley to pass low speed emisisons.