I have a 1990 suzuki 250r quad racer and it's not the best bike to have when you have close neighbors.. that being said I'm looking for a after market exhaust that will help quiet my quad down a bit. Thank you

 

Stock is usually the most quiet. Maybe try re-packing the silencer?!
Find a buddy to bring his 4 stroke with a aftermarket pipe over and do a lap or 2 around the house. The neighbors won't hear your 2 stroke again..Lol

 

...packing is oil soaked or gone....and about the four stroke being louder ....yep

 

There is some silencer systems out there (which is mainly just another muffler connected to your stock system) but the age of your unit I don't know if one would work. Check Amazon.