Im working on a friends car and we are trying to get the best setup we found a good deal on some ported 5.3 heads and we going to pick them up this weekend this is his setup.

full bolt ons
ms3
ls6 intake
4.10
m6

what kind of power is he looking to get from the heads.also is there anything we need to look out for ? i believe he has stock 5.3 valves in them well they work or will we need to change them out?

.. heres a small description from the guy we are buying them from says about them.

i've spend lots of money on port and polish work, valve job, new valve seals, the seats have been reangled, and they've been resurfaced. these heads will make great power on a ls1 motor. for those of you who are not familer with this mod it will basiclly bump compression on the motor there for making more power. alot of people will argue that the 5.3 heads wont flow as well as a 5.7 which is true when they are stock but when ported and polished the actually flow alot more!