I am currently installing the subtank system described by Shawn_MC (on an 03 CRF450.) (Thanks Shawn_MC for the information.) I have some questions concerning drilling and tapping for the 1/8 NPT fittings. Do you drill all the way through the bleed hole (or just deep enough for the fittings?) Do you separate the cap from the spring/washer etc. before drilling (or just be careful and clean after drilling?) What about the spacer on top of the spring? It currently covers part of the bleed hole? Did you trim this at all? Finally, is the hole very close (after you drill) to the edges of the cap? It appears that there is going to be very little metal left after I drill. Any help is appreciated. Thanks.