For those who run the Boss .28, the needles in the carb are the needles used in the MR Ninja/ Grp .21. If you can source the Ninja/Falcon/GRP .28 needles, massive improvement in not only tuning but Power!!! I have all the 28 mentioned and the Boss is wayyy tame vs the others ., until you put the proper needles in it. Tonight I was putting a tune on it and noticed the lsn sticking out wayyy farther than my Falcon that I was running last weekend, then I checked my Ninja and GRP 28s and they were all about flush, had me scratching my head . Then I grabbed my GRP .21 and the lsn was sticking out like the Boss 28 so I checked the GRP 28 needle and Ninja 28 and its vastly different when compared to the Boss. Then I compared the Boss 28 to the GRP .21 lsn....identical. Swapped the GRP 21 hsn and lsn and Boom show time! I guess this is another way they made sure the others were superior to the others as far as performace..? Maybe these were assembled when the "correct" needles were no longer availible ..?The Boss crank pin is the same as the Ninja 28 BTW. I'll time the crank soon and compare to the Ninjas as well as the sleeve but from eyeballing the heights of the ports its Identical. Long story short, swap the needles and it feels and sounds like the Ninja/Falcon. My Grp is a tick tamer than the others. Cheers Guys!!