Well Dustin @ Whipple will disagree with you there. But hey, go nutz....

Might be cheaper in the long run to replace head gaskets. You may be tempted to check cylinder walls while you are in there. Hard to beat the Cometic gasket for boost applications. You can also get Cometics in various thickness to change CR slightly.

I went with the cometics when I did my hp500efi.

Check your email!
Regards,
Steve

Stock head gaskets are aweful on 500EFI's... Had them going at 185hrs on both motors when I freshened the heads....Do a search on the board and you will see plenty of confirmation.

After seeing the merc head gaskets I would replace them just to be safe even without a blower. I am suprised they hold up at all.

500
blower, cometic head gaskets, new head bolts, good fuel, 700 plus h.p , and hold it.

What he said, and change to crane 651 spin 6k and throw down 850hp on 93 Octane @8# with no chiller (8-71 4% under)..... definately "on the edge" though....

Well, no doubt it would be a good idea to change the head gaskets..I did too..used the cometic .051 and I also went with the JE dished pistons...but it is not a have to....if the motor is strong now you would most likely be ok, for a short time...but one way or another, you will be freshening and changing head gaskets sooner or later.

As per Dustin @ Whipple the other small concern are the pistons. Rings postion more than the material. I didn't swap pistons, only head gaskets. Oh, and went with Dart Aluminum heads. Stock heads are cast and don't disipate the heat generated by the blower as well as aluminum. They also don't flow anywhere near as good.

Touch wood, my engine is stong and I have seen a 14 mph increase in a single 28' boat.