Well heck thats a pretty nice gain especially since you have heads already. It will be a real nice surprise at the track when you pull a couple tenths and people think your car is bone stock. Your right about the springs-thats the worst part about doing cams-I can't stand it!

 

I still think the LS6 cam is a great sleeper cam especially if you can buy it used. The 02-up LS6 cam will pick up decent gains (more than 10-15rwhp) over the stock LS1 cam. The key is to rev it to 6500-6600 rpms. With the LS6 cam, full bolt ons and a Yank Y3200 my car dyno'd 348 rwhp unlocked. The hp curve was nearly flat until 6500 rpms where the stock cam dies off dramatically at that point. It ran easy mid-low 12's at 109-110 mph all day without a problem. The best part is no tuning is required (but recommended). If you can get the parts cheap and want to attempt your first cam swap, this is a great cam to start with.

FWIW- I paid $150 for a used LS6 cam and springs.

 

i got mine for 75 shipped with pushrods and springs:-)