Like said above...shearers are definitely the way to go(thats whats on my 421 with 35pwks also) Cpis are also great pipes, though i havent ran them on my 421. Both are topend pipes. As for the lock up, if you dont want to go all out direct drive(spendy investment) go with a slingshot lock up. It will fit right under your stock case and there is a guy selling one on the bhq facebook page for like 125 bucks. Hopefully your shop knows what they are doing with the porting. There is a local yamaha shop around me that claims to do great porting, but if you dont know what your looking for they will just do a clean up port and charge you for a full on drag port. Check into some site sponsors on here, they have great reps and have fast turnaround time with excellent prices. I have personally delt with cameron at redline, and kevin at HJR. Both are great guys. If you live in oregon redline also has a dyno the he can dial your bike in on with jetting and gearing so it is perfect for you.