Its going to them for a couple upgrades so will ask the questions as to if its had the stage 1 kit.
MMC stage 1 has square cut exhasut tips whereas the stock are angled.
If you're getting the "gravel" sound (probably starting at about 5,200 rpm) that's pinking and stock exhaust.
As discussed in may threads - drill out the front baffle or swap to MMC Stage 1 or G56 to free up the engine.
