you definately need one if you have f/i ,or youll end up with oil all over .even if you have just breathers,theyll end up filling up with oil /condensation and leaking all over.plus they stink with braeathers only .it helps the smell to have a catch can.run -8 from drivers side then -8 from the pass side ,merge them together into a 10- 12- into catch can.easy.theyre are other methods ive seen that may be more affective ,but this seems to work descent for me.good luck
mods:2004 sierra ext sb,20s ,big brake kit w,hawk pads,air bagged,2006 6.0 lq4 swap,vortec supercharged10psi, air to water intercooled w/ dual electric fans on it ,snow meth injection kit,60lbers, e-fans ,big radiator swap ,cam 218 /222 548/550 comp .hardened prs .1.85 comp roller rockers ,guideplates ,crane double springs,trans 4l65e built .pacesetter l/ts true duals w/x pipe and magnaflows,14 bolt rearend swap ,3.73s,aroemotive fuel pump system w/elec.fuel controller and bypass regulator a/n fittings, taylor 10.5s interceptor gauge,aem w/b a/f ,autometer boost/vac NELSON 93 OCTANE TUNED .