I'm buying a replacement motor, and have the option of getting either a S4 block or S5 block.

They are longblocks (everything but the turbo and accessories)

The car is a S4 TII with an Rtek 2.1 720/720 setup, and a BNR turbo setup at about 12psi.

The S5 has the lighter higher compression rotors
The S4 has the lower compression heavier rotors, but their stronger and desirable for higher boost.

S5 block has hardened gears, and a couple other block upgrades.

Should I spend a little more and get the S5 motor, and swap the front cover, S4 electronics, etc, or is the Juice not worth the Squeeze in the long run.

I'll be running this motor for about a year while I rebuild and upgrade the current S4 motor. Just on the fence about which one to go with, and need a second opinion.

Thanks

 

S5 if you plan on going over 350whp rear iron on s4 is weak