I am looking at a Garrett TO4E 57 trim compressor, P trim exhaust wheel with a .69 A/RI currently am running a T3/T4 60-1 hifi stage 2 .62 A/R I think. Right now it starts spooling at like 2800 and reaches full boost right before 4000. It really has very little lag. I really like that but I want more power. I only made 333.1 @ 25psi with that turbo. I want over 400rwhp. The turbo I am looking at came off of a Twin Turbo Viper GT-S that dynoed about 850 at the wheels.

I think if anything, it should spool faster. The T04E is a better designed housing, and the A/R is relatively the same. But I'm not a turbo guru, just guessing.

25 PSI of boost and you are only getting 333 HP? So far I've heard of 3 KA's that are putting out over 300 HP out of a T3/T4 at only 15 psi. The same turbo on an SR should yield similar gains at the same boost.

As far as the T04E you are looking at, the compressor map shows a very wide efficiency island. It can handle some high boost with really good efficiency as well. I'm running a T04B with the same turbine you are referring too and the lag is not bad. It will hit my full boost of only 6.5 psi by 4000 RPM, and even sooner in higher gears. At higher boost levels, you will probably get a little quicker response out of the T04E compressor.

I'm not sure what kind of manifold you are running, but you may also need to consider that the turbine flanges are different between the T4 and the T3. Not to mention, the on-center turbine of the T4 will probably move the compressor side out of alignment with your intake piping. Unless you want to dish out a lot of money to make everthing fit, I suggest invesigating different T3/T4's. Or even looking into why your's is running so poorly. At 25 psi, you should be doing well over 400 HP. The 60-1 compressor seems like it may be quite inneficient at 25 psi(Pressure ratio of 2.7) according to the compressor maps on the turbonetics page. It doesn't show the numbers on the map for the 60-1, but 25 psi puts you well out the peak efficincy island for that turbo. Perhaps a T3/T4 with a .82 turbine A/R Stage III Trim, and a T04E 57 Trim compressor section. You can play with the turbine specs a bit and go smaller for quicker repsponse, but if you plan on running a lot of boost, I'd opt for the bigger turbine specs to allow better flow. If you're looking for max power, you don't want the turbine to choke the motor.