I'll try putting stock tires back on and see what happens. The modified stock exhaust you can see in my pictures. I took and cut the back out of the stock exhaust and then welded a down pipe on it to keep it from blowing on my bumper. Then I tought it was a little loud so I drilled some holes in a freeze out plug and drove it up in the down pipe. Now it sounds great but I don't think I messed up the back presurre It only flows a little more than stock. Thanks for all the info.