KRE's are more "customizable". Kaufmann will put them together as per your specs, or close to them. They will also help you with those specs, based on your bottom end and desired performance. Regardless of brand, be sure to have a qualified person check them out before installation. Chamber CC's are rarely what is designated....and there is PLENTY of material left for porting(on the KRE's). I had to send a set back due to larger than ordered chamber size. No way to tell without a burette(spelling?).