KA's done properly are stout. 20psi is putting you over 440whp if done right so you don't need that much. A 3071 is a good match to a KA and spools lightning fast. Get a good set of cams, build the motor properly and tune it properly and you're singing. I've built several SR's and KA's for customers and I'll tell you if you want over about 260whp reliably on a KA you need to build it, it will hold it but not for long. Built properly you can run about 430whp easily on 93 octane. Dollar for dollar you're better off with a KA or an LS1/LS2. When you get around 400whp you will have to build either an SR or KA and get all the turbo stuff, ECU, and such. You can drop an LS2 in for about the same amount of money, have 400whp, and it will last longer.