EDITOR'S NOTE: I received an e-mail from Steve H. in November '09 indicating that another MIG had recently tried this mod, only to discover that the H.K. internal baffles were too narrow for the J&P baffles to fit inside. H.K. may have changed their standard baffle since this article was written. Proceed with caution!
The process is actually a combination of two mods - an added baffle and the
"sink strainer" mod, which has been around for awhile. Looking inside the strippers
from the end you will see the reason they are so loud, the baffle is unobstructed
with only serrations on the outside providing sound deadening.
J&P Cycles sells a mini drag pipe baffle that will fit inside the HK inner pipe/baffle fitting snug against the start of the serrations. I bought the 4" version seen below.
I drilled 2 holes in the flange where the diameter of the baffle reduces and drove 2 stainless sheet metal screws into the serrations to hold the baffle in place.
I then cut down 2 stainless steel sink strainers slightly larger than the diameter of the HK inner pipe and drove them in with a friction fit. I added some exhaust putty to the edges of the strainers to keep them in place.
The result is a quieter sound. I can’t quantify the reduction in volume, but I did record the sound at each step and the difference is significant.