I've heard the stock covers will work if you "modify them slighttly". What do you have to cut/file? And how much of it? Thanks for any advice!

 

Take off the valve covers, and flip it upside down. Where the bolt comes in through the top of the cover, there are supports. At the base of the support, the metal flares out a little, making it thicker than the rest of the support. Make little cuts on each support, so that you can take a pair of pliars and straighten out the entire flare, making it inline with the rest of the support. Thats all you have to do. Complicated to explain, but simple to do once you see it. good luck

 

will this trick work with other rollers rockers as well?

 

I havent heard of actually having to clearance the stock covers with any other RR. The problem with the Pro Mags are that they have a wide body, and the supports on the cover, wont slide down between the intake and exhuast rockers. We are just narrowing the part that slides between the rockers so that it fits without hitting.