Increasing backpressure?

[PHXDEMON]

I recently installed the nitto midpipe on my car along with the stock header and a tanabe madallion axleback. It feels like I dropped a lot of torque from 2-4k RPM and I usually don't rev higher than 4k Is there an easy mod I can do to temporarily inscrease some backpressure to regain some of that torque until I am boosted? Also for those of you who have the midpipe are you getting 100% success on getting rid of a CEL with that anti fouler deal the garm sells on his website?