Intermittently lower performance mid-range and top-end

I recently upgraded to an SV1000s (2005) because I wanted more power than my previous SV650s (2001).

With the 650 there was like a problem where it was down on performance very noticably especially in mid-range and top-end power (60 - 70% of power is my guess)
I figured it was the bike or carbs that would've been the problem here. Anyway, now having the 1000 ofcourse is a lot more powerful, although during my last ride It felt like it was having the same symptoms as the 650 had. Noticably lower mid-range and top-end power.

Due to the fact it's showing the same symptoms I am ofcourse wondering if I am doing anything wrong with the bike, as in my riding style for instance that makes it behave like that.
I have to say I do blip the throttle a lot, even at low speeds or in traffic (cuz of the sound ofcourse). Could that be the issue here? Some rides it feels like full power, but last ride it was definitely lower on power. And by intermittently I don't mean every other minute or so. For example yesterday I recall it rode fine the whole 50km (30 miles) I rode. But today it felt slower the whole ride, at least when I went WOT.

I just wonder if it's me or the bike's 'fault'. The bike is completely stock apart from LeoVince slip-ons. 56k km/35k miles on the clock.
I look forward to any response, thank you in advance.