Just did TSP 1 3/4 longtubes on my lq4 2500HD 4x4. They fit really well and are really quality built for a lower price range stainless header. Lots of clearance as far as the frame, steering linkage, trani lines, and front drive shaft. They did make contact with the heat shield on the driver's side motor mount but it was easy to bend down and clear. The 2 center plug wires need a 90 degree boot to clear the primary's ( I actually trimmed down the boots and heat shields on the plug wires I had and made the work). As far as the passenger side all that I had to do was trim that ear on the side of the trani about 1/4 to 1/2" and a little bit of tricky manipulating on the dipstick tube. Over all I'm pretty satisfied. They also came with good quality AC Delco gaskets but no bolts. I haven't fired it up yet because I still have to finish running new pipe to the mufflers. I will update with more pics soon and with gains after some tuning!