ive been readin around and saw some posts about a loss of power with true duals on the HEMI's...i just dropped my truck off to get dual exhaust...but not true duals....just y'd out from the cats...same deal with power loss there or not? and one more question...what difference does the length and the diameter of the tips make?

 

I have an 03 and some exhaust dude told me the same thing. The engine/comp doesn't like true duals. I think it's because 03's have only two o2 sensors. If you went to true duals the sensors would endup ononly one of thedown pipes and the computer would only be reading half the the exhaust.Later models have 4 sensors, a set for each downpipe, and splitting up the exhaust on those is no problem.
As for your question you shouldn't see any power loss as long as you have a free flowing system. The length and dia of your tips will change the sound of your exhaust. How and how much will it have an affect? I don't know. I've only had one set of tips. I imagine the bigger the tip the deeper/echo-like sound you will get. Like a megaphone effect.