I have a 2006 5.3 w/ Magnacharger. I am currently running the 3.4 pulley. Am I able to downsize to a 3.3 or 3.25 without additional tuning? My truck is basically stock with an outlaw CAI and flowmaster. Any input is appreciated, thanks in advance.

 

No, i wouldn't recommend that at all. Dropping to the 3.20" pulley would be the next jump but it does require live tuning, either on the dyno and/or street.

You are going to want to take care of the transmission before you do something like that though.

 

I would do it, but thats just me. I don't retune for upping the boost alittle. I run the same tune for 7 psi as I do for 10. My A/f looks fine and no knock, so im not too worried about it. But you may not be as lucky as me.

 

I went from a 3.7" pulley to a 3.25" without a retune and had no trouble. Later I installed a wideband and found there actually was a lean spot the truck would hit going up certain hills around here at just the right speed. HPTuners fixed it pronto. I would say you would be OK, but if you want a retune, either do it yourself, or check with your shop to make sure they do part throttle and variable load calibrations. Many speed shops only tune for WOT, which would not provide a proper street use calibration.

 

you should be ok changing just a little bit like that. you know that the stock maggie tune is rich to be safe so you should be fine. i personally would get a tune whether you pulley down or not.

on a side note - ive got a 3.3 pulley ill sell ya.

 

I would definately get a retune.. Just a tune over the Maggie/Superchip tune will be an improvement. I would go with a 3.25 puleey and go from there. That would probably get you about 7-8 psi. Work your way down in pulley sizes in small increments getting tuned each time

 

Should I go to a 3.3 or straight to the 3.25?

 

I went from 3.4 to 3.2 and gained ~ 1.5/2lbs boost. It felt like a big jump to me.