With these higher ratio rockers Scoprion told me the resulting lift is in the 555/565 range. TSP did the tune. I also installed a 25% ASP underdrive pulley. The truck sounds great even though it still has stock exhaust manifolds with cats. The customer is very happy with the results. He said it really starts to pull around 3.5K RPM. One piece of advice if you change a cam on an 04 Silverado/Sierra. The JPR tool(which costs $100.00) won't work. The cam only came out 1/2". I used some 5/16" steel rods($3.50 each at Home Depot) and the cam came right out. Don't waste you money on pen magnets or the JPR tool. Just get the rods and be done with it.

 

why wouldn't it work? we just used 5/16 dowel rods on my 07...

 

Dowel rods are fine too, but unless you sand them down and make them as smooth as a baby's ***, small slivers may get stuck in the galleys... Or you could not use any rods or dowels at all and just spin the cam until you hear all the lifters pop up and pray to the lifter gods that they don't fall...until you get the new cam in...

 

I'm not sure why the JPR tool wouldn't work in this 04 Sierra. It has worked for me in other LSX engines. The cam only moved about 1/2" before it hit a lifter using the JPR tool. I tried removing the JPR tool several times and spinning the cam multiple times in both directions, but it didn't help. Once I inserted the steel rods the cam came right out. It obviously made the small difference I needed to get the cam lobes and journals past the valve lifters. With the JPR tool inserted I could hear the cam clunking against a lifter as I tried to remove it. Another tip off was when I was inserting the JPR tool I could feel it brush up against the tip of the JPR tool as I was pushing it toward the back of the block. This only happened on the passenger side. The rods I bought at Home Depot didn't have any burrs on them so there was no prolblem with them snagging on the block as the were inserted.
I would like to know from DozerDan if your 07 has VVT or AFM. Not being able to install an aftermarket cam in the new trucks with VVT and AFM has been one factor that has held me back from buying a new truck. That and the fact that I've been waiting for GM to offer the 6L80E or T56 in the Silverado in something other than a 2500 HD.