Chainsaw Repair

Hello all, my brother just picked up a brand new 372xp to buck some firewood. We fired it up and cut some wood, ran a couple tanks through it. It's running a bit on the lean side on the low end,  I checked the intake boot and impulse line for a leak and found nothing wrong, didn't expect too as this saw is brand new.  we adjusted the low screw to max setting for richen, the saw likes this but has adjustment stops on the carb. I figured i'd trim the plastic tabs off the adjustment screws and then warm up and adjust the saw. I pulled the air filter covers and found Husqvarna is using a new carb that must have limiters on the inside or? there are no more tabs to trim on the outside. so here's the question, can this carb be modified to have full adjustment or is it better to replace it with an older style carb? i don't know if the older style carb would run on a new engine, did they change anything in the engine that would prevent me from running an older style carb? the part numbers on the saw are walbro# RWJ 4B 311. any help or suggestions are welcome.

Poulan carb tool is the dog for those WJ carbs.
Shep

This thread had some good info on new 372 XT tuning and carb tool etc.  http://chainsawrepair.createaforum.com/husqvarna/new-372s/