Powerlog is better than any PEM, and I wouldn't even mess with a rear PEM.
x2 The powerlog is the best for the front. I was impressed with mine. I wasn't expecting much gain from it, but it was noticeable.
I wish I would have stuck to my guns on the rear PEM. I recently got one and tonight I was extracting an O2 plug in it and I don't see much that is done to it. And it is a reputable PEM from the now defunct Hulkspeed. I'd like to see a stock one to compare, but I can't imagine you could gain more than 1 or 2 hp from porting the rear. Unless the EGR tube really butted into the #6 primary. I don't think I will even go to the trouble to install it.