I've heard slap them in and go...

What about porting the stock heads? Dont the PRC stage 2.5 flow way better than the 243/799? Prolly could send yours off and have them ported for just a lil more than buying a new set of 243/799's.?

I like the advice of buying real heads, so ill probably leave the stockers on till the time comes to swap them!

Your stock heads are more than enough for your cam. I like your idea just put new springs in and live with it till you later want to buy some real cnc ported heads.

I would leave the stock pistons and mill your 862 or 706 down .03 with stock size gasket. Boom your at 10 to 1 compression for what ever you mill price is $50-100

The 243 and 799 do flow better than the 862 and 706 but not much better. No where close to a cnc set of heads. You will probably get more from the compression jump than the head swap of stock to 243s

The 5.3L heads will make more lowend tq than the 243s. Velocity of air flow is higher with the small ports. The 243s would make more top end hp.

I would consider selling the ls6 cam and going with comp 216/220 on 114. Can find them all day long for $370

Your putting long tubes on the car right?

I'm not sure which to do, I've heard mill the heads or swap the pistons... Or both lol. I'll stick with the ls6, I've already got it and it was only $100, I knew there were better cams. And deffinetly long tubes

$100??? haha ok stick with the Ls6 its a good cam. If you ever decide to put new cnc ported heads on you could upgrade the cam as well.

Stay with the stock pistons and mill the 862 or 706 "which ever you have" heads since your on a budget.

The money spent on new pistons could be put towards a new intake manifold, Under drive pulley, new gears, stall, transmission rebuild etc you get the idea

What intake do you have? Truck?

What are the driving habit plans? the car a dd, dd and toy, or track

If it is a dd that you race stop light to stoplight the truck intake would be best due the amount of tq it makes, but the ls6 intake will make more hp. Idk if the truck intake will fit under the car hood.

Did you get a pcm for the 5.3L, timing chain, lifters,

How many miles are on the 5.3L?

The 5.3L is a small cubic inch motor so big port heads will hurt lowend tq and make it slower than stock heads from 1000-3000ish rpms

Bumping compression will increase tq and hp through out the whole power curve and its only a $100ish to do so. Best performance gain for the $$$$

Everything im telling you is my opinion in regards to a budget build.

You can make any motor as powerful as you want with a ton of $$$$$ the hard part that most of us have is making a lot of power with lil $$$$ haha

One more thing I would run 2.5" true duals with xpipe. 3" is to large for a N/A 5.3L. I regret doing 3" besides how loud and awesome they sound lol

For the headers I would recommend pacesetter quicktrip ceramic coated headers. You can get them for $400-500. They dissipate heat better than stainless steal and painted and look brand new for a longgg time I have had my headers for 40,000+ miles and the still look new

Lots of great info thanks! I'll call local shops about milling the stock heads! I've already picked up a ls6 intake with 36# injectors and a ls1 tb. I'll be getting ls2 timing set, ls7 lifters, ported oil pump, pushrods, and all the gaskets. The car will still be a dd as well as a toy. My plans for a tranny are still up in the air because they are so costly, I might try a used 4l60e with a stall already in it. That way ill at least have a core to get rebiult later on if it craps out.

It all depends in how close they are to the originals that being replaced. If the weight is off by much, then yes it would be best to have the rotating assembly rebalanced. If the intention of the rebuild was to just get you from point A to point B it wouldn't be that big a deal, but for performance use where stress is multiplied by rpm it becomes very important to have a balanced rotating assembly. I would at the very least weight the old vs new pistons and use your best judgment.

Your going to need shorter pushrods if you mill the heads. Get a pushrod checker. should be aroud 7.25-7.5 if you mill .03 but dont take my word for it