I recently bought a mugen bpipe for my 95 GSR coupe. The owner said it was off of the same car in japan and there is a mugen badge on it. The bpipe lines matches at the catalytic converted but after the resonator the bpipes increases to 2.5 inches all the way to the axle back. I have a comptech axle back that is 2.25 inches. I brought it out to a muffler shop and he told me there are numerous ways i can approach this problem.

1. He proposed to cut off my comptech and run a 2.5 pipe all the say to the muffler itself. This means i will have a dead set up.

2. He can cut off the 2.25 flange on the comptech and replace it with a 2.5. This meanst that i can remove the comptech whenever i want.

3. He's gonna cut off both the 2.5 and the 2.25 flanges and weld it as one whole piece.

Basically there are many ways to approach it so I am asking for some feedback on which path i should go. Will there be any airflow interference? Please help. Thanks