my 97 xj 4.0 l has the black resonnator on top of the throtlebody. what is it good for. does it increase power? can i scrap it and put a rubberhose from the 91 + in there instead?

 

Main thing it does is help soften noise from the intake... At highway speed with it removed, you could hear some whistling from the intake at highway speed. If you are still going through the stock airbox, you should not hear it anyway... just mainly a muffler for the intake