I pulled the 4.8 out of my 99 silvy this weekend and installed a Lq9,cammed,ls6 intake 42lb svo's.My stock rail had the regulator built in, but I went with a single f-boby rail so I got a vette filter/regulator and plugged that in my stock lines.I took the truck to the dealership to use there fuel gauge , it had 60lb idling and if I touched the throttle it would drop 5 psi. Should I upgrade to a 255 intank or do something different. Stock pump has 105,000 miles on it. Help me out guys are the 42's too big, jesse did the tune.

 

60-62psi is pretty common with a 255 pump at idle.

You should see 58 just off idle , but depending on the gauge, it could be off 1-2psi as well.

Your concern should be pressure at full throttle. If it drops too low, then you need to consider upgrades to the rest of the system.