I was debating between :

SRT Intake w. Race ECU

-or-

Injen Intake w. SAFC II

which one would better suit my GS400? I want the most HP/TQ gains

what do you guys suggest?

 

SRT intake with the Race ECU.

some members have seen HP gains of up to 20-30 hp if im correct?

 

SRT

 

At least with SRT you know what your getting. With the SAFC, it all depends on the tuner...

 

For simple plug and play and not having to worry about mounting a display unit SRT all the way.
I don't think the S-AFC will add much more if you you leave car stock but the S-AFC has the potenial to benefit more if your adding headerand intake. But like stage3 said it has tobe tuned right on a dyno