Just bolting on the header - no further mods? - about 2 hp....
In order to make it worthwhile you may want to couple that with a low restriction cat, freer flowing muffler, mandrel bent exhaust - you could make 10 hp...
Ya think? I don't know, with the tiny ports on the '91 heads I don't think you'll see much inprovement. You might free up some restriction, but the real bottleneck is in the head.
I noticed that when I put the longtube on my '90, it liked to rev better and would rev higher easier, but other than that I wasn't impressed with the power gain.
I noticed that when I put the longtube on my '90, it liked to rev better and would rev higher easier, but other than that I wasn't impressed with the power gain.