I read that every Japanese manufacturer has reduced the core size on their mufflers by 10mm to meet the AMA’s 94 dB sound limits, but I noticed that the end cap of the 2011 Suzuki RM-Z450 still has the same large opening that it had before. Did MXA mean that say that every manufacturer except Suzuki went smaller?
Suzuki’s secret perf core reducer.
We never said that every manufacturer has reduced its core size, because, in fact, KTM has increased its core size by 3mm and Yamaha has the same muffler for 2011 that they had in 2010. But, Honda, Kawasaki and Suzuki have reduced their core sizes by at least 10mm. The reason you think that Suzuki has not made its core smaller is because they hid their reducer deep inside the muffler. By inserting a 10mm smaller core into their existing core they got the sound reduction they were looking for and didn’t have to stamp a new end cap.