2012 Mitsubishi Lancer Exhaust Piping Diamter

So I am doing a muffler delete on my car, and im pretty sure that the diameter of the stock piping is 2.5 inches maybe 2.25 inches. So it will stay stock throughout the whole system until the axle, where I will be putting an "axle back straight pipe". The pipe I have for that portion is 2 inches in diameter. From what I understand, a car that produces between 100 and 144hp can use a 2 inch diameter exhaust system throughout. Obviously my car is right on that edge at 148 hp at around peak RPM (6000rpm peak is 6500rpm) so im just wondering if the 2 inch axle back straight pipe will be a problem in the form of back pressure and all that fun stuff? The range to pipe diameter scale is for a full system, this will be just a small portion while the rest of the system is running the stock 2.5 inch piping so from what I understand it shouldn't be a problem but I wanted to ask a professional.
Thanks in advance!