Apathy

Ok, I got a new 88 gxl w/ about 25k on da rebuild. It drives but put on a straight pipe and a hks hp muffler w/ a resonator off of a dodge ram. The car sounds really good, nice and deep--not raspy, but still silent at a stop light. Anyway, I put it on last night and I noticed alot of smoke coming out of my tail. Dark smoke, and my friends said I was busting alot of flames. Only thing is, the were pretty long cause I could see a couple out of my driver side mirror. I think I am running way too rich. How do I turn it down? I dont wanna get anymore tickets.