The reason why I said 75 was because I will be using the max extreme
Having a Max Extreme doesn't change the power level you should 'start' at. so I would start with about 50 percent max and see how it went.
It's NOT a good idea to limit the peak using the Max, as its better to use jets to do that. I'm not doing the install and I don't want to start low and get bored quick so I have to take my bike back 170 miles away to powerhouse to have bigger jets fitted and have the max extreme re set up again for me.
99.999% of my customers change the jets themselves and unless the kit is fitted without consideration to the ease of replacing the jets, it should only take you TWO MINUTES to change them yourself.
The best way to proceed is to have Lawson fit the smaller jets and then just take the bike for a test ride and see how it feels and if you think you need more, he can then change them for you there and then to 50s. On 25 you won't need to use the progressive delivery and even if you did, it would only require a VERY SIMPLE adjustment to the Max to have it better suited to the bigger jets.
The Max is designed to be EASY to use and intended to be adjusted by the customer to suit different conditions and/or use, so I'm sure that after a few minutes of instruction from Lawson, you'll be able to change the jets and the progressive settings yourself. although I have been told the max extreme is easy to use but I'm not that computer literate.
I designed the Max myself and I designed it so that ANYONE could adjust it. I tested it on a customer who was a builder, who had ZERO capability with anything even basically electric but within a few minutes and WITHOUT any instructions, he was able to use it. Admittedly that was an older unit and we've added many more features to it now BUT the basic operating arrangement is still just as simple.
All you have to be able to do is read and press buttons. 
I thought I could just limit the power to begin and add more as I feel I wanted.
Although that's possible using a Max it's best to ONLY limit peak power by using jets. 25 hp gain is not a lot I think.
LOL - you've a lot to experience to gain with a WON nitrous system - LOL
What you need to keep in mind is the following;
1) Your bike ONLY makes that amount of power at peak rpm.
2) When your bike is doing say 4,000 rpm and you grab a fist full of throttle, your engine may only be making 25 HP, so if you activate the nitrous at that point you are instantly DOUBLING the power
3) When we claim 25 HP we are being conservative and it's more than likely that you'll actually make more
4) What is most impressive and what will throw you off the back of the bike, is the HUGE TORQUE increase that ONLY WON nitrous can make.
5) Even most of our bigger bike customers are 'happy' with what they gain from 25 HP jets
6) When I first started in business I sold my kits with 80 HP jets and it resulted in most bikes running SLOWER 1/4 times, because the power increase SCARED the riders to death and that was on BIG capacity high powered engines!!! My bike was 107 bhp at wheel standard and after it all was rebuilt and 6 grand later it was 140 bhp and I wasn't that impressed with the power gain.
That's because NA power ONLY delivers an increase at the TOP END and usually REDUCES the low end torque and power but WON nitrous is ENTIRELY DIFFERENT. 
I do go down the strip with it and I want to get off it and start whipping it . !! But my mate has a 190 bhp bussa that scares the sxxt out of me every time I use it . So I was gauging power by that lol .
You'll be able to EASILY beat that Busa with JUST 25 HP from your WON kit, at worst it will be close. 
