Bipolar electrolyte capacitors against too bright tweeters?

Hello, I have the Rainbow SLX 265 Deluxe on an μDimension 5.4X and find the tweeters really too bright. First I simply put them to listen on the dashboard and tried out different positions. Against the disc, indirectly, up… Nothing really 100% was there. Then I simply built them into the original tweeters “schat” of my Golf 3. Of course still sounds too grim. So it bites right in the ears. On the EQ from the radio I can still save a little bit of the time. but it’s still nothing true. Now someone has told me something about bipolar electrolyte capacitors that you should order in the thickness 2.2mf and 250V to switch them in front of the tweeters so that they don’t take the middle high-tone range with you anymore. Has anyone ever done this before? Opinions? Experience? Thank you for every post, jelly