I just installed a Kimpex aftermarket muffler on my AC 300 to replace the original which had a bunch of holes rusted in it. I find this one as loud or louder than the old one. Is there anything I can do to quiet it down a little? Maybe a little extender on the exhaust pipe? Does anyone have any ideas to try that won't cause any problems with the engine?

 

They have a collection chamber on the market that bolts on to the back of your muffler in a horizontal fashion - cost a bit of money tho'. I would look around to find some flexible steel exhaust pipe and just extend it. You can build a collection chamber out of a small coffee can, (a little bit of solder or welding and steel exhaust pipe/tubing and you are in business).

 

So adding a little extra pipe won't hurt anything? I have read here in the past about needed the proper type of exhaust to prevent burnt valves or other problems like that.

 

Adding length will not hurt. Too short with no back-pressure could cause a problem if the timing was not adjusted.

 

I read online somewhere a guy welded a washer to the end of his exhaust pipe and put some steel wool inside to muffle some of the noise.....claimed it worked somewhat too.....is this crazy idea?

 

Until the steel-wool rust and crumbles to nothing - unless it was stainless-steel... lol..
You also can cut a section out of your exhaust - say 12 inches long, then neck it up to a larger pipe and then neck it back down to your pipe size. i.e, 1 inch up to 1.5 inches and back down to 1 inch. It is an expansion chamber and also acts like a collector - but it will deaden the sound and not restrict your exhaust. - neat, get a little zip and tone it down at the same time.... lol..