I don't think I've tried to modify guitars. My cheap Jay Turser does me as is. I've old Fylde Falstaff that needs restoration (bellied up 15-20 year ago and action is high). Only thing I felt inclined to do with it is try different strings - I like the D'Adario 85/15). I'm happier with GDAE tuning on mandolins, etc. but can get guitar through at least a few session paced melody lines like St Annes's reels with a pick and finger pick a freight train. One thing that really defeats me I'd lke to do is finding those subtle chord changes used in Irish music. It's me than the guitar that (if it a correct term...) that needs upgrading/pimping.