Immediate gains. You will need a PCM specific to the cam though depending on how agressive the Cam is. I run a S/C car, so I cant speak for the N/A 3800's, but the whole theory of swapping a cam for one with more lift and duration can only be good provided you're able to get that PCM tuned to the car. Once you get that PCM it will take a few days for it to "learn". Depending on what cam you put in your car, the powerband usually moves up, so you may be feeling disappointed with the cam because the car's not shifting where it should be. I ran a "Re-programmed" PCM from PFYC (the one I had prior to my mods) with my Stage 2 cam after the rebuild, while I was waiting for my PCM from INTENSE. The car ran like "Dog-dung" (I'd like to use more colourful terms, but I guess I cant here, LOL) until I got that Stage 2 PCM in and learned. The difference with the cam I have, and shifting at 5800 as opposed to the now 6500 RPM is night and day. I would be leary of changing the shift points on a stock engine though. Some may say it's alright, but I already grenaded one engine, and I wouldn't wish it upon anyone. Good luck!