They won't do much for a pre-99 car (5-7 hp or so), because it has a more radical cam. They do a lot for 99+ cars (12-15 hp) since the cam is milder in the newer cars.Pinto said:There are two kinds of roller rockers, there are adjustable and non adjustable. The non adjustable rockers are cheaper. When installing adjustable ones you will need to adjust them up to the right pre load. The adjustable ones usually require some shimming. The give you more lift and move more smoothly than stock rocker arms. They are not very hard to install though. They won't make a noticable difference on a stock car, with a cam though they make a big difference. Here is a link to the install instructions for them:
the best place to get them is at RPM Mustangs, if you're going non-adjustable.
www.rpm-mustangs.com has 'em for $250
You'll need the adjustable RRs if you're planning a cam swap.