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Mufflers have been a bit of a problem for MMRA in the past.  There was nothing built specifically for minicup cars that was from a well known manufacturer and available nationwide for a reasonable price.  Fortunately that has now changed.  MMRA asked RLV to produce a muffler specifically for minicup cars that would not need any modification whatsoever.  They have done it and the price is even a few dollars less than the old style go-cart muffler we were modifying for minicup use.

The new muffler is RLV part #RLV4120

The price from Mountain Machine Service for the new muffler is $36.95

In the future, this will be the only legal muffler for MMRA races.  If you have one of the old style RLV mufflers, you can continue to use it, but anyone who wants to purchase a new muffler should use the new part #RLV4120.

It is encouraging that MMRA minicup racing has grown to the point that a major manufacturer like RLV will build parts specifically for our cars.  Thank you to all of our members who helped make this happen and to RLV for their support.

Questions and Answers

1.  Why did MMRA want a new muffler?  -  The old go-kart RLV mufflers we were using came from the factory with 4 baffles inside.  That restricted airflow and power so Mountain Machine recommended, and MMRA approved, allowing racers to remove two of the baffles.  This meant everyone had to hassle with the muffler instead of just welding it on.  It also meant racers were "inside" the muffler which is an opportunity for knowledgeable racers to gain an unfair advantage.  MMRA wanted a simple muffler that was ready to install on a minicup car, and can't be modified or tampered with in any way.

2.  I have an old-style RLV.  Is it still legal?  -  Yes, MMRA would not say it is legal one day and then make it illegal the next.  When you need a new muffler however, please get the new part #RLV4120.  It is cheaper and dyno tests show a slight improvement over the old style with 2 baffles removed.

3.  Why does the new muffler cost less?  -  The new muffler has fewer parts and RLV was nice enough to pass the savings along to the racer.

4.  Do I have to run a muffler?  -  No, the MMRA rulebook is unchanged.  If your area requires a muffler, or you would like to run one, you can.  If not, you are still welcome to run a straight pipe.  Either way, make sure the total overall length of your exhaust system is at least 28 inches long.  Check with your engine builder to see if a muffler might help increase horsepower on your engine, and if so, try out this new RLV.

5.  I have other questions - No problem, just send e-mail to