I think my turbo is sized perfectly for a 5.3... I can keep it out of boost at anytime, except when towing, yet the spool is very quick when I want it. It is a Q-trim 1.0a/r 70mm. A P-trim .96 70mm will spool significantly sooner and from less of a load on the engine, which isn't a bad thing. It really just depends on how you want the truck to act. If you did go with a 76mm, I would keep it at a .96 P-trim. You could even pick up a .81 a/r housing for it, to get things started a little quicker.

 

magnum p trim 64.5/74.2
Q trim 67/74.2

the outlet on the q trim is a little bigger

 

Good info in here. Both will work fine, but if it's a true DD i'd look into the 70. It will be there ready to come online at each street light if you ask. The 76 won't be to far behind it, but you'll be pushing the on the go pedal longer before it joins in. Both will meet your 500HP goal and have another 100HP+ potential.

 

Agreed... if I did not get my t76 for a steal..I would have went 70mm..power difference minimal and boost spool time is quicker.

 

You can also get a Magnum turbo in a 72mm compressor for a nice middle ground.

 

Like others have said either will work. You can make 500 with a 62mm turbo. A 76mm gives you more room to grow then a 70mm will. You can always run a small a/r housing if its too lazy for you.
If you get a smaller a/r go ahead and buy the larger as well.
You will need it later in life.

 

70mm w/ .96 ar..... You'll love it

 

I've got the same cam as you and a similar stall converter. I would go with the 70mm .96 a/r if you plan on keeping your current cam.

 

Wow. Tons of great info here. Thanks. Im on the fence regarding the 220 cam, i am worried it will bleed off too much boost. Alpinestar, if you had to do it over would you still go with the 220?

 

I'm running Tr220, with a mp 76 96ar. Made 486 at a little under 10psi. Running 13psi now and it runs strong. I am considering swapping cams though to see if it makes a diff.