Yea, I'm all stock, I did the elbow removal plus k&n filter. I noticed good mileage and hp gain, and also when i replaced the pcv valve. When i put the super 40 on i noticed a decrease in low end torque. Also , it seems to shift between gears around 50mph. If i let up on the gas, the rpms go up above 2k, but if i put my foot back down, they'll go up to about 2300 or so then shift down into 4th. it's really annoying and i dont know what to do. I get about 300 miles to the tank, im currently at 283 and have a quarter tank left, but ill fill up tomorrow to be safe. I want to go to borla, but i want to make sure that muffler that ldub has has better backpressure. I guess if you have too little bp, it has a negative effect and flows too much. who knew