I just fitted a FULL DR D NS 4 after using a full yoshi for 6 months on my YZ 450 2014 Didnt like the yoshi with the silencer insert, removed that & was way better sounding & power. Is however very abrupt of the bottom, too abrupt in fact mainly out of corners, (stock maps).Also think the yoshi build quality was poor. Where the first join is from the engine, vibrates to the point ive had to re weld the little lug that holds the join in place. Both joins dont seal properly even aft sealing them the hi temp gasket cement, TI syst.After about 30 hrs Someone PLS tell me you can remove the silver DR D silencer, (already removed spark arrestor) & how ? First ride with the silencer in, thought was worse than stock. Felt all chocked up & like it added no benefit ! You can not remove the spark arrestor on the ns4. it is welded in. you could cut the screen but then it would be permanently removed. The stock pipe has better low end. but almost too powerful, the Dr.d seemed to be better mid and top.