Pops and Crackles

Rice Krispies in the fuel tank?

As for not getting too illegal, it may help to know what the laws are in Austria, to be able to advise? Noise levels, carbon/particulate emissions, that sort of thing..

I do not want to destroy the exhaust or remove the baffles.
The mod should be reversible.

Fitting a de-cat pipe to bypass the collector box under would be reversible, and could result in more popping, esp. on the overrun. It'd make the bike run lean, though, and I couldn't say whether or not it'd be legal.

there is actually no cat inside and a decat pipe dont work with this exhaust i think.

An intermediate pipe could always be fabricated to bypass the collector whether or not there's a cat inside, but how much the airflow would change if it's only a small volume with no cat, baffles, etc. inside it, I don't know!

I have the twin acra and you can remove the baffles / db killers.
Remove the small rubber plugs near the end of the cans, and drill the weld out ( the weld is to stop the baffles being taken out)
You can then knock the baffles out from the exhaust inlet side with a tube which slides over the baffles . But be warned they are very tight, best to do in a vice.
There was some threads on this site showing how to do it, or google it.