I did quite a bit of research back about 15 years ago for something that provided a performance gain and possibly an MPG gain without sacrificing low end and with as little modification to other areas as possible.
What I came up with on paper was the Comp XE 256.
I recently acquired one but have yet to install or run it.
Since my research, I've heard from a couple different people that the Lunati version is better "under the curve".
Theoretically, you could install the Comp 256 with no other mods- gear, converter, machine work to heads, even springs.
Since it's a dual pattern, it doesn't even need headers. I'd run 2/2.25/2.5 duals, though.
The factory said dual exhaust was worth 20HP on a 318, I'd take that.
I always question why people recommend over .500 lift cams for "one step above stock" 318 builds.