The reason it's hard to get more NA power from the motor is because it's all ready a beast. It is just a 1.8L motor and makes 190hp all day long on 91 octane fuel... I digress
As far as the cams go on a stock car, stock tune, etc = not a great use of funds, IMO.
On the supercharged cars, we're doing some custom tunes for stage 3 cams on the stock ECU over the winter. We have been doing custom supercharged tunes on the 2s and 3s w/ the standalone for quite a long time. The best gains are with forced induction and the cams certainly help there.
From an NA standpoint and to really make an appreciable difference, you need cams, more compression, custom tuning, etc and that will turn a street motor into a race fuel only motor... Plus, I'm pretty sure we're (kold-fire USA/BOE) the only ones doing totally custom tuning on the stock ECU, and we have no plans to do a "big NA" build/tune for anyone anytime soon. There's just not enough demand for such a tune to dedicate the time to it. That means you're going to be confined to a standalone for engine management-- a great solution for some, but not others...
I have not degreed the MWR vs Piper Cams, but they're near identical. Both companies set the lobe centers to about the same as stock, so you can drop them into a stock tune and the car WILL RUN-- just not optimally for the cams. The MWR cams are running a tiny bit more lift as I recall. I think the duration is comparable across the two. Power output should be about the same.
We have Stage 3 MWRs in the race car (Still street legal). It drives and idles just fine. In fact, the idle is truly as smooth as stock at around 1,100 RPMs. You'd never know it has big cams in until your either pulling on a car you "shouldn't be" down the straight or until VVL kicks in. The induction noise generated by the big Stage 3s at VVL is almost defening. Absolultely insane-loud induction noise when compared to stock cams--- or anything else for that matter!!
There's a nickel or two from KS...