Well, I'll take all the good news I can get and since the intake and exhaust mani's are the same. That helps. After I get some maintenance issues taken care of I plan on getting that intake. It woulda been nice if the heads were the same since 4.3's are probably more plentiful but oh well. It's still good information. Does anyone have any cam specs on the 4.3, 5.5 and aftermarket 5.5 cams? Depending on the tolerances on a 5.5(is it interference or not) one can achieve a more aggressive cam profile by simply providing a set of cams and paying someone to regrind them and all the better if you already have a proven set of specs to regrind to.

 

Now it's time to switch gears on this. Underdrive:
Is the stock crank pulley just a bolt-on pulley or does it have the balancer built into it?
Next the evosport accessory kit, what is the ud ratio? Generally speaking one can ud 12-15% with no problems. 18% and up is risky without doing the proper research.

I have a nasty feeling it has the balancer built into it. How much is the AMS 1:1 crank pulley? I'm thinking if bad comes to worse I could get one, mill it down 15% and cut new grooves into it. Laslty, anyone know the diameter of the stock pulley?