dom

I currently have a G&G TR16 R5 which i plan on turning into a DMR. At the moment i am looking at changing the basics. This being the inner barrel and hop up bucking. I am looking at a 6.01mm tight bore barrel, is there much difference between these and a 6.02 or 6.03 ? And hopup bucking i was thinking madbull blue or red. Are these products any good ? what would you suggest ? anylinks to good websites would be great. Thanks Dom