Can I do this to an LT1 that just has a full exhaust and intake? What kinds of gain would I expect from it. Thanks guys.

 

I've heard most 1.6RRs well clear the value cover. I'm running the GM 1.6RRs ( out of the LT4 kit) with my stock covers. The stock rockers are 1.5 and not a roller. I don't really know how much it well help but i'd guess at like 10-15 whp.

 

Yes most if not all RR will clear. Pro Mags being Wide body RR need the little support braces bent straight on the valve covers to clear the RR otherwise they fit. The stock roockers more or less are not a true 1.5 rocker. I think they're a little less. When I swapped to 1.6s on my car I noticed that it pulled better above 3000rpm to redline. I'd imagine they'd be worth a noticeable gain in RWHP.
Matt

 

Oh yea will will pick up a good 10hp