Hello, I've got a quick question. I installed a turbo back 4" exhaust, and now I noticed black smoke when you step on the throttle and a strong diesel smell when sitting at the drive thru. Milage hasn't dropped a lot , Its not making oil, Power seems alright ( did notice a loss after going up to 265's last month) Truck is stock except for tires and exhaust. 2004 GMC 2500 HD EC 4X4. Is this normal or is somethig starting to go amiss. Thanks in advance, this is a great site.

How much smoke? Is it a lot or just a little bit?

makes perfect sense. Mine is an lly, and I had a cat that got deleted, but you have removed the stock muffler that does eat some of the HC (diesel smell) and your new muffler is basically a straight pipe, so the muffler is no longer blocking the smoke.