I have used the 122 on a 5.3l and it works great with a 3" pulley. About 12 psi with a 224 cam. This is also a front mount 90mm TB configuration.

 

this might also help you out.
https://www.performancetrucks.net/fo...d.php?t=425976

whats the difference between the j tube and the front mount as far a performance?

so would the 3.0 pulley on the 5.3 with out a cam give it more or less boost? my guess would be more.

 

Never tried it with out a cam. Also Never tested back to back on the j-tube vs. front inlet but I would imagine the front inlet is more efficient. Team magna sales will step in and tell by how much pretty soon I am sure.

 

The faster you spin the blower, the more boost you get. If you add mods to make the motor breathe easier, the boost will go down a bit, but the power generally goes up. A rear drive blower adds a couple of extra pulleys that can be used to spin the blower faster. From my understanding, the 122HH can be spun a little faster before it loses effeciency. A bigger blower spinning slower will probably be more effecient than a smaller one spinning at a faster rate. The smaller one will build heat quicker. High IAT's limit power.

 

What year 5.3 was it that you put the 122 on?

 

06' 799 heads.

 

i disagree with the rep go 122 and pully it high for less boost til you are ready for a built bottom end i wish i went 122 now im upgrading soon

 

a 122 is too much blower for a stock 5.3.

 

I'd say it depends on your goals. If you are looking to just bolt on a blower and a few bolt on's and call it good, go 112. If you are looking to do a cam, headers, etc. down the road go with the 122. This is important especially if you might even step up on cubes down the road. So many started with the 112 and ended up switching. Avoid the costly switch down the road. It might even be a consideration to go with the TVS 1900. Not very big, but better than the MP112. It has seemed that a 2psi gain as posted is common when going from the MP112 to the MP122. That's not a huge jump. Alot of guys run a D1SC on a 5.3L, a MP122 isn't out of reach for a 5.3L. Look at what Parish is doing with his "stock" 5.3L.