While I have the rear end out so that I can install the new IRS suspension I'm looking at the exhaust. At the end of the stock head pipe the diameter reduces quite a bit as it works its way top the muffler. I would think that this would cause some restriction of the exhaust flow. Now would be the best time to redo the exhaust and go with a larger diameter pipe. My question is would this reduce the back pressure to the point where I would feel a drop in performance. Or would I be OK with leaving the exhaust system alone. I have a stock 2020TG with a gutted head pipe and V&H slip ons. My down stream plans are to add a torque cam, air cleaner and tuner.