Hey Ben,
Thanks for posting this here! The thing is, that the higher the output power of an engine is, the more narrow the power band is and usually also, the higher the power, the higher it is ranged in the RPM. For example a stock scooter engine has about 5hp. It peaks at about 7500 rpm but it has a very wide band. You probably have 4hp at 5500 rpm already. This makes it very easy to adjust and find a matching exhaust. Basically you can't do much wrong unless you go to the extremes.
Then there are racing cylinder. Some of its power is produced due to the increase in bore (70cc), but most of it is due to port layouts. A good sport cylinder kit can produce 12hp, however the power band is much more narrow. it will produce 12 at 10500rpm and but at 9000 rpm it might only produce 6hp.
The amount of rpm is highly dependent on the exhaust design. The exhaust allows the engine to rev higher (it also can move the powerband around a bit, but that's not so important right now) and reach the ideal rpm for the cylinder kit.
The genius of the CVT engine is that (like the name implies) it is a variable transmission. Unlike traditional shifters, it changes gears (or ratio) automatically. This is why you're scooter goes faster when accelerating but sounds like it is staying at the same rpm (it actually does stay at the same rpm).
To your problem: If you say you want to pull wheelies and stuff, this usually means you need quite a bit of power. The Aerox has a Minarelli engine, which is great for tuning and performs very well out of the box already. Like you said already I'd say the Stage6 Cylinder Kits are a very good choice because of their price, quality and performance.
The Sport Pro MK2 produces good power and has quite a lot of torque and a reasonable power band. It is also a good match for the 17.5mm carb and works with a good range of exhausts.
The Stage6 Racing MK2 on the other hand produces quite a lot more power and it also feels stronger because it is more peaky. Tho, it is harder to setup as you need to hit the power band exactly and it also requires a higher revving exhaust (Stage6 R1200 or Yasuni C20). It will also consume a good bit more of petrol and requires more maintenance (high rpm is really not so good for an engine).
If you are not so experienced with carb jetting, CVT transmission setup etc. I would suggest to go with the Sport Pro MK2. You have a good choice of exhausts here. The Sport Replica works well and is not too loud, the Sport PRO (non replica) is hard to find but performs even better and the Yasuni C16 or even C20 would also work if you upgrade in the future to the Racing MK2 cylinder kit.
One thing with the minarelli engines is the crankshaft. By default it uses a 10mm gudgeon pin, which is ok for some tuning, but can break when running under a lot of pressure (Racing MK2 with a good exhaust). Thus I would recommend to replace the crankshaft to a 12mm one as one of the first steps. A full circle crank also reduces engine vibration at high rpms.
To sum things up and recommend a setup:
- Cylinder Kit: Stage6 Sport Pro Mk2 (Racing if you dare
- Exhaust: Stage6 Replica or PRO (non replica), Yasuni C16 or C20, or R1200 if you want higher performance but they are quite loud
- Crankshaft: Anything with 12mm full circle, tho the Stage6 HPCs are good
- Bearings: Get a set of new bearings (NTN or SKF) when replacing the crank. Ideally some high performance ones like the Stage6 and such
- Intake manifold: Get a tuning one. I believe the stock intake mainfold is restricted to 12mm.
- Airbox: Read about tuning your airbox and make sure to clean it regularly
- Reed Valve: Replace the stock metal valves with kevlar/carbon ones, or get a sport reed valve block. No need for the expensive ones.
- Variator: You need to adjust the rollers to match the rpm of the cylinder kit. You can get a roller kit, or directly get a sport variator (Stage6, or Malossi. Malossi is better I think but also pricey)
- Clutch: Harder clutch springs bring the sensation factor as the engine clutches in at much higher rpm. If the stock clutch is worn, you can switch to a sport clutch. Stage6 is good and les sof a pain to handle than the Malossi one.
- Clutch Bell: The clutch gets crazy hot in the summer, especially when riding in the city. Get one of these CNC clutch bells by Stage6, Polini or Naraku.
It's quite a list but the small parts like springs, rollers and such are really cheap. Each of the items listed I would consider a must-have. Regarding your Gianelli exhaust: You could give it a try with the Sport Pro MK2. Giannellis are usually very compatible. Performance would be comparable to the Stage6 Replica exhaust.
Hope this helps for now. Let me know if you have further questions!
