youre right the requere a minium bore of 4.000" because the have big valves and the valve angle,so you can NOT use them on a ls1

Is anyone making headers or exhaust manifolds for these LS engines? How about starters and other marine accessories?

The rumors seems to indicate this is the last year of the 496. And with these:
http://www.gm.com/explore/technology...LY6_Marine.pdf
http://www.gm.com/explore/technology...LS2_Marine.pdf
...it does not seem like the LS is going to have problems making lots of power.

Thanks for those links. I did not know GM was moving that way with the LSX engines. As for power they can make it!
My LS1 has a basic heads and cam package and makes
420rwhp @ 396rwtq which is around 475 hp at the crank out of 346 cubes. A friends 402 LS2 with AFR 225 heads and cam makes 567rwhp @ 521rwtq which is well over 600hp at the crank. He traps 130+ mph at the track to my 117.

Great info guys.I think more people will be using this setup.Thanks for all the help.

about the headers a orderd a pair of cmi headers after calling them ,the tell me the fit .
about the rest marine acc.I ll get mine engine this week and then I look but it s based on the bolt patern of a 5.7 so the bellhousing must fit ,but when I have it I will post my results here for the raw waterpump I have a serptine driven mercruiser oem maybe have to made some mods but c ant be much but I ll post it all .
by raylar the also did it but don t know what heads they used had tried to call them serveral times also send e mails but no results but that s a very nice looking engine (lsm 550)

bor