Small Engines (Lawn Mowers, etc.): engine muffler noise, sound proof, muffler

Question
i have a one year old B&S generator with a 15 hp B&S engine. It starts great and runs great.  But is it ever loud!  are there any options to reducing the noise (short of building a sound proof building) that will not void the warranty or hurt the engine?  the engine is a model 246435, type 0111E1.  thanks

Answer
There are a few options but they can get expensive.  Refer to the links below.

http://www.jackssmallengines.com/quietmuf_index.html

http://www.alpharubicon.com/altenergy/gensetquiet.htm

I liked the car muffler idea, cheap, but you have to have a welder and it's not very portable.

Let me know if this helps.
Eric