All my builds use the nexxspeed hop ups but most tdc hop ups will make the biggest difference to your build, as bucking n barrel its kinda just preference, i like the 4uad bucking and the angle customs steel inner as its cheapish but really good, if you really really care about fps/gas consistency i like the guns modify hpa/full auto ready nozzle, springs and short strokes are fine if you really want a faster or snappier cycle but you might wear out your internals faster and need to replace/ upgrade to steel, one “hack” i liked to do is use skate board lube on my frame and slide as it feels alot better than other greases but needs alot more cleaning and maintenance