Ive been fighting with some really bad fuel economy on my truck. Its down around 11mpg with mixed driving.
I recently had the pump rebuilt so I know its not that. The injectors and the valve lash check out too.
It seems like the issues started when I had the head gasket replaced. They decked the head .015 and used a .020 gasket.
I know when you deck the head you need to be careful of valve protrusion and thats part of the reason for a thicker gasket. The other part has to do with optimizing for boost. Problem is the truck is driven easy around town a lot and the mileage is awful. I think the reason for that is the lost compression.
Does anyone here run 500-600hp on a stock thickness gasket? Do you think studs and orings on a stock thickness gasket would hold up to that kind of pressure with 65psi?
Ive got hamilton's springs on there. I think theyre 110lb. and Ill probably keep the 3K gov springs in it so Im not worried about valve float.

 

I'm pushing 80psi on stock gasket with ARP 2000 studs and o-rings.

 

I got some other feedback too that makes me think this should be a safe combo at 650hp which is what my goal is on the truck.
I think the loss in compression is whats killing my low end power and economy.
Self-inflicted wound there.