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Recommendations? The first one I'd make is to get a cam at the same time. Heads are usually only good for ~20rwhp on their own at best....with a cam you're talking well over 100rwhp in most cases.
Assuming you REALLY can't do the cam, you should look into having the LS6 heads ported or at LEAST milled to increase compression. This will magnify your gains from the head swap.
All of that work and $ for 20rwhp is usually a bit dissapointing. For another $100 or so of milling, you'll get larger increases in torque and hp.
What Billdog said, don't expect much from just an LS6 head swap. A 224/224 cam on a 114 or 112lsa with a set of beehive springs would be a nice compliment and with a tune would hardly affect street manners. Just something to keep in mind.
I am not going to recommend a cam like everyone else, do it when you want to. I will simply say that I bought 243 heads that were brand new. I am not unhappy with them, but I wish I would have just bit the bullet and bought better heads. If you are going to do the swap, give serious consideration to making a real upgrade (like AFRs).
Other than that, why are you putting in LS7 lifters?? And new lifter trays??
If I were to (and may) start from scratch a another (C6) vette I would buy big $ heads and a small cam. Smaller, even, than my 224.
I just did what you are about to do, see my post in perf section.I gained like 45 hp/30something tq by adding stock 243 heads with valve job, yella terra 1.8 ,ls6 intake and b&b shorties
if youre worried about the idle and driveability at least go with a ls6 cam....can be had for 100bux and wellllllllll worth the change over a stock 99 cam...looking at prob a 50 hp boost over stock ls1 stuff
i have ported and polished 853 heads (work done by DRM) will 243 heads give me any more flow? i plan to have them ported and polished too
i also have the 226/228 cam from DRM
^^From what I have read, ported and polished 853 heads will outflow the stock 243 heads. However, all else being equal the LS6 heads should outflow the 853 heads.