As you can see in my signature picture (truck completely stock) I had no problem breaking the rear tire lose.... Then I cut the muffler off and welded a straight pipe in there... since then, I cant do this... seems like my top end is a little better, but I wouldnt think I changed the torque that much if at all... Any thoughts?

your suspicions are correct. you have changed the peak power range from low/middle rpms to mid/upper.

i removed the spare tire and then i could do it... not that I want to replace those 20" rubbers....

I had the same exact problem with having the straight pipe in place of the muffler. I did like the top end power, but I got tired of the sound getting to higher speeds quickly so I put the stock muffler back on for a short time.

i know on mine i used some 4inch pipe smashed down to fit and welded it all up. still have same torque as before.not sure why exsept that maybe it gave me some back pressure going bigger than back to 3 inch pipe.

o and i reused the stock 3 inch tail pipe after the 4 inch