Both bikes have the race tuner. The 15 actually has higher numbers, as far as horse power. But it's not as quick as the 10. The 10 is more fun to ride and will get to 80mph a lot faster. I'm thinking of some 777s cams and flow the heads. That should wake it up. Heck right now the 10 gets better fuel mileage right now. I'm thinking the 15 will improve with some more miles on it. Only a couple of thousand right now.
The 777 cams are a higher compression cam and it will not work well in your bike without major engine work.
Save your money and get a good tune first and don't look at HP look at torque.
There isn't that much difference between the 2015 stock cam and the SE255 cam.
Lift .511 intake .511 exhaust
Duration 212 intake 233 exhaust
timing - intake 02 BTDC/30 ABDC - Exhaust 43 BBDC/ 10 ATDC
SE 254E cam
Lift .535 intake .536 exhaust
Duration 224 intake 234 exhaust
Timing - intake 01 ATDC/43 ABDC - Exhaust 50 BBDC / 04 ATDC
SE 255 cam
Lift .556 intake .556 exhaust
Duration 211 intake 235 exhaust
Timing - intake 06 BTDC/ 25 ABDC - exhaust 48 BBDC/07 ATDC
As you can see the stock cam is closer to the SE255 cam in duration also the intake open before BTDC and close earlier ATDC which is common with low torque cams, the SE 255 has a little more low end torque because the intake opens and closes sooner then the stock cam, and the low end torque is what will get you up to speed faster.
But in all reality there isn't too much of a difference between the SE 225 cam and the stock cam except that the stock cam will have a little less on the bottom end and a little more top end.
I have a 2015 engine in my 2008 with the stock cam which is the same cam your'e using and I like the way it performs but that's JMO.