Axleback Exhaust issue?
 

Ok so I have a 2014 q60 and I had a Top Speed Pro 1 axle back on it for about 9 months. As time went on, my Rpm's would drop when I stopped(mostly abrupt stops) and when I would turn into a parking space. It would even stall from time to time. The longer it was on, the louder and more sloppy sounding it got. So I put my stock one back on. No stumbling, smoother acceleration and no stalling. The top speed exhaust had no leaks. Do our cars just hate canister style mufflers?

Your right, they hate that too.But even when I cleaned both of the above mentioned, it still did it. As soon as the stock muffler went back on, those issues were gone. Very strange.

Your symptoms are not those of an axle-back. Don't know what to say.

Yea I'm totally stumped. No worries though, it runs great.

Well, if you are increasing the outflow, you need to increase the inflow.
To fix the problem with your axle-back, you'd be wise to install forced induction. FI solves most problems like magic.

Don't get me wrong, it didn't happen alot, I just noticed that it didn't happen at all once I put the OEM muffler back on. The car runs perfect, smooth as silk.

Don't think hes going from a top speed axle back to Forced induction just a wild guess but.....

Exhaust leak on gaskets?

mine has the same issue too, but not all the time but it's annoying. TB and MAFS cleaned, new battery, suspecting fuel pump??