How to decrease exhaust noise on highway???

I have a magnaflow muffler on my '96 XJ. I spend alot of time on the highway at about 75 mph, and the interior resonance is pretty bad. What would be some good measures to reduce this? Is there any sound deadening material that can be put up under the muffler and stand the temp? Will that even help? How about half inch carpet padding for the cargo bay? Or will I just have to get a quieter muffler? I really don't want to lose the subtle rumble, but I hate the loudness at high speed. Is there a really good performance muffler that is quiet in the XJ on the highway (dynomax, borla, gibson)? Any input will be great. Thanks

Kind of went through the same thing you are -- Although I never thought my exhaust was loud at cruising speeds -- just had too much drone at 2000 rpm while accelerating.

I ended up putting a magnaflow glasspack in front of the magnaflow muffler. Now it's quieter (but not silent) while driving around but still opens up and makes some noise when I want it to.

It was a tight fit -- basically the hiflow cat, resonator, and muffler look like one long piece...

In my case I also have a Borla header and a hi flow cat -- both supposedly increase exhaust noise over the stock stuff.

Matthew

Thanks guys. Will a double wall tail pipe really elliminate all the highway resonance? Can any shop put one on for a decent price?