Should I change out my heads to lower compression so I can run more boost on my LQ9
Or would it be a waste of time and money?

 

I would if I where you. I'm a boost junky. Got to have boost. Lots and lots of boost. J/k I have a set of lq4 heads that will do the trick. 317# casting, they are just sitting in my garage. $350 plus shipping. I just thought I'd throw that in there. smile.

 

what will the compression go down to?

 

j4nash...you already have the 317 casting heads on your motor (lq4 and lq9 use the same head), to drop compression on your motor you'll either have to get heads with custom-cut chambers or stack head gaskets (NOT recommended) as the 317 casting already has the largest chamber of all LSx production heads (71cc)

 

nothing, the heads for the LQ4 and the LQ9 have the same cc chamber.
you need the dish pistons from the LQ4 to swap out the flat tops of the LQ9 to get a ratio of 9:48 to 1

 

so without getting dished pistons or a custom set of heads there really is nothing i can do?

 

pretty much

I've seen f-body guys run 12-14 psi with proper tuning on 10.2:1 motors...you just have to be conservative with the timing to prevent detonation