How much HP/performance loss can I expect by going with shorty headers vs. full headers of the same 1 5/8" diameter?

The way I understand it is: loss of torque below the peak with shorties but an increase above peak vs. full length, all else being equal.

I'm sure you would also have to take into account how good the rest of the system is, though. If the system flowed like crap, you would probably see a loss all the way around.

Chad