If i bought just rockers and pins from a ls1, would they drop right into my 06 gxp?

 

Yes, they would.

 

Are there any performance gains to be had going with them? Along with like a tune, plugs Catless dp, ?

 

No, there's no benefit, as the stock LS1 rockers are the same ratio (1.7) as the LS4.

You could get some aftermarket 1.8 or 1.85 rockers and you'd get a noticeable bump in HP. Just be sure to not get the cheap made-in-China units.

 

anything else we'd need to run the 1.85's on an otherwise untouched engine? springs/retainers/etc? pushrods?

 

You'd need springs. An inexpensive set of GM yellow springs will be just fine. Stock pushrods and retainers will work just fine with this setup.

 

Whats the best rockers to get? And part# if you have them.

 

Go for 1.85s ive heard the harland sharps are good.
You will most likely have to pull the oil baffles out of valve covers to clear. Not sure of the part number.

 

Is that the same for the 1.8 ratio rockers as well ??

Thanx

 

I've heard some 1.8s fit...but I can't confirm.