G26 midpipe upgrade - what is rasp?

I have a 2024 M440i GC. When I bought the car, I wasn't very knowledgeable in modding, so I opted for an axle back M-lite MPE (essentially just a muffler upgrade). It sounds great, but I want things to be even more dramatic without failing emissions. The next upgrade I want to do is a midpipe upgrade.

For the G26 platform, the only midpipe with a resonator that exists is from DCE Parts. I can't find much information on them so I'm not sure how reputable their product is.

The other alternative would be a non-resonated midpipe from AA. My mechanic is advising that I should find something with a resonator as otherwise, there may be significant rasp. I've been looking at various videos now and I STILL don't know what rasp is. I'm not sure if it's something I'll like, or if it's something that I'll regret.

The reason I don't want to get rid of the MPE just yet in favor of a full exhaust kit is that I paid a hefty amount to get the MPE installed at the dealership. If anyone can explain rasp, or know of any good clips, I'd love to see/hear them!