Originally Posted by duramaxtuner
A Cp3 only has capacity for 600 RWHP, a Cp4 has a capacity for about 550 RWHP although the Cp3 is known for being slightly more reliable.
If you are going to run twin turbo's I would think the 10mm Cp3 would be the best fit, since you have room to grow (capacity supports about 750 RWHP).
The LML transmission is much more stout than any of the previous models. Realistically running them at 550 RWHP (which is 150 RWHP over stock) is about as far as you will want to take a daily driver.
i guess it is really down to what the OP wants to do. with 600+ HP you are in the bent rod/cracked piston territory. a CP4 can keep her in the more safe zone but the pump may not last as ling as a CP3 doing the same HP. also the drop in fuel pressure would not be good. with a CP4 she could have a nice clean burning 550ish HP due to being fuel limited and having a lot more air. with the CP3 she can push it up to about 650 or so. if she goes with the CP3 and limits the tuning to about 550-600 HP then she would have a more reliable setup then CP4 rout with a little bit of room to crank it up if she wants to take it to the strip.
my 2 cents