Hello. Need some advise. I need to do head gaskets on my 05 5.3. I use the vehicle to tow and is my daily. I need a little more low end power to get up and go while towing. Plus I would like some more power for when I'm off road. What heads can I use other then my factory ones to get some more power and still use my factory tune ecu? Thanks in advance

 

There really aren't any. Especially not more low end.

Youd probably get more benefit from getting rid of the lame factory tune, than anything you can do to the heads.

 

Well poo lol. I kinda figured so. Thanks

 

The heads on your engine are the best for a stock 5.3. Smallest chambers of any LS head, plus ports that give best velocity. If anything, do a bowl blend on your heads. It is 60% or more of any good port job.
The ONE thing you could do if nothing else is .040 head gaskets which will give a skosh more compression but more importantly better quench to better avoid preignition.
But that's about it before going further into the engine. Factory tune will still be fine.

 

Maybe lower rear end gears for better low end power?

 

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First: Towing with a tiny engine? Small motor needs to SPIN. you NEED 4.56 gears. ( that was a period )
Second: Manifold pressure: 10 or 11 PSI should be enough, and will run on 90 octane.
Small engine wants to act BIG, it's going to need some boost. Turbocharger, or Belt drive, take your pick.

 

While the heads are off, I'd cut them .020", bowl blend the ports, have a good valve job done, use the .040" head gasket, and upgrade the springs.

Like you've heard, 706/ 862 heads are really the best thing for a stockish 5.3. Hell, they're good for up to 6.0, depending on your goals.

 

Exactly. He has the right parts that need a little massaging to best advantage. And none of what we've mentioned will affect the tune a bit.

 

There’s a lot of power to be found in a tune. GM sets the OEM tune for mileage and emissions, not max power.