Finally got my DMC Alien full exhaust for my 300EX today. How hard is it to re-jet the carb?

 

Not hard, get a couple of jets, one and two sizes bigger than stock, also a one size bigger pilot jet. The factory air box only has 2 little frame tubes feeding air into the box, put a couple of vents in the lid to make sure you're getting all the air in that the new exhaust will flow out. While you have the carb apart, shoot carb cleaner in all the passages to make sure it is nice and clean. With the small size of the stock exhaust, you will notice a nice bump in power and throttle response.