You need some type of engine management to see any gains with the cams. The ECU is probably freaking out and dialing stuff back. I can not give you a expert recommendation as I have not seen one product stand out that everyone is using for NA. If you are concerned about emissions, stand-alone management is not an option.
The one I have been reading about is SSAFC (the one without timing retard for boost). There have been a few threads talking about NA tuning using this and I believe Ken might have a NA map. I believe you can not map the closed loop map, only the open loop (when you put your pedal all the way down). There was talk of being able to trick the ECU into open loop so you could tune more of the range then just full throttle, but i am not sure how. You will need more things to go with your piggy-back computer. A wide-band sensor and A/F gauge, a dyno tune, and driving tune with a laptop. Since you had to dial back the twiggy cams crazy overlap so it will run, you have lost some of their magic. A good tune will allow you to fix that, but remember you have to idle higher than normal with though cams. I believe the lowest I have heard is 800-1200 rpm.
I hope I helped a little with the information I read about from other massive threads, and threads long gone.
