98 gst 118k miles..no mods at all besides upper IC pipe.. I've noticed during the day if I get on it, I wont see any smoke coming out the back but sometimes at night if someone is behind me, i'll go WOT and can see some smoke from my muffler hitting the cars headlights behind me.. The smoke seems to be kinda grayish close to black... I know these cars run rich but I just want to know if this is "normal" or if something might be wrong. It doesnt smoke at idle or normal driving or eveb at WOT in the day.. maybe I just cant see the smoke in the day. My oil pressure is fine and there are no leaks in the engine bay. The turbo(T25) spools just fine with no noise or hesitation.