Hey Ron, and welcome to Inliners! These later generation inlines respond well to many of the same mods that V8's do. So pretty much anything you would do to a 350, for instance, will give close to the same results, like headers, and electronic ignition, hotter camshaft, and possibly even a 4 bbl.intake and carb. Also, if you are going to be tearing into the engines internals and boring it out and doing any head work, the usual 3 angle valve job and bowl porting helps, as does the bolt-in "lumps" that are available. There are also, several on here that have put turbos on these engines, so being a diesel mechanic as mentioned in your post heading, you can appreciate what a turbo can do i'm sure. So there is really no limit as to what you can do to these engines for performance upgrades.