The stock stem is VERY WEAK. Adding Rox Risers will add leveage on the stem causing it to bend VERY easy. TRUST ME i get ALOT of bent LTR450 stems that i turn into anti-vibe stems. Here is what i have found.
+1 stem with stock bars - is highest you can do with stock cables with out manipulating throttle and clutch mounting position.
+1 stem with CR high bars - just alittle higher then completely stock set up.
Dana Creech bars - same height as cr mid bar
ATV bend - same as CR double hi
I dont have the Flexx bars to know for sure. Remember Flexx bars are semi adjustable as far as height goes depending on the dension you set the bars at ....... BELOW IS JUST A GUESS ......
+1 stem with Dana Creech bars - SHOULD BE about same as stock maybe a tad higher
+1 stem with ATV bend - SHOULD BE very close - HIGHER then stock for sure. MAY NOT FIT WITH STOCK CABLES.
With this being said ......
+2 rox riser with dana creech bars MAY FIT with stock cables but i dont think so
+2 rox riser with atv bend WILL NOT FIT with stock cables just a guess
FUELATV