You do only 2 exercises for quads !! Smith Machine Squat & leg Press only !!
You have great results from doing that showing on your legs.. Great Keep it up bro..
How many times you hit them a week and how long have you been bodybuilding..?
yeah you only really need those 2 cause by the time you try leg extensions they're taxed as it is. I used to do leg extensions but if I were to do them I'd have to put them infront of everything just as a warm up and that rather pointless to me. Plus they just don't feel right on the knees when you go heavy.
I just do legs once a week and I've been doing it seriously for about 9years now.