Are you talking black carbon build up?? I've never had anything like that, just chalky mineral build up.
I'd try Brake Clean if its black build up

toilet bowl cleaner

Lysol Gel Toilet Bowl Cleaner. Will make your props look brand new as well!

What do you guys use to bring back a aluminum trailer? Have a evolution that needs some cleaning up. Used a polish and it turn rag black fast so I think it's not sealed.

CLR in a spray bottle, I think its a chemical reaction that makes it work, so spray on agitate and repeat until its clean...it will take a few times with that process,

https://www.summitracing.com/parts/lqp-0847

I have used this many times on snowmobile tunnels, there are a lot of similar products on the market search " aluminum cleaner and/or brightener

thanks guys will try the recommendations

3M Metal Restorer and Polish is the best thing I've found for cleaning tailpipes.