I had the exact same setup with an e303 about 3months ago, and the stock cam is way more fun to drive around town. There is night and day difference in the low end power and torque, tell you the truth I sometimes think I lost a tad power up top..but if I did.. its real real hard to tell or notice. But as for gaining overall power and torque between idle and 3500rpms..I defienetly gained some. Besides, if you are going to go cam.. go with something that matches your rpm band of choice. For me, it was 1k-5500rpms..
^ I was refering to a stock cam.. it keeps the power band stock. Apposed to most others, e303 for example, that move the power band from 3500-6000 (roughly depending on what cam), which is a kick in the pants increase of power, but sacrafices low to mid power..for me, I like going being able to stomp on the gas at 2k, where the crusing exhaust tone is, and actually moving. Not creeping up to 3500ish rpms and THEN getting some momentum.