i'm having no problems, i just like how they look, and i've also heard they can (and heard the opposite) be better for your engine. if my car is running rich, would the addition of unmetered air actually make it run a little better? have one, but when when i downshift, i sometimes get a CEL for a sec, but it disappears right away when the rpms drop. i thought it was probably from my o2's being further back now, (b/c of LT's), but i dont get any codes for that. only codes i get with KOER is 94 (R), 44(R), and 33(R). 33 is EGR Valve not opening properly. 94 is from clutch not in (i think) and 44 is thermactor fault, but i removed it all. no codes with KOEO. could the breather cap be throwing a code? should i switch back to normal oil cap?