It's all about how much you can afford to spend Boss. A stock, ported cylinder and head mod will more than double the HP of a stock Blaster. Parts are easy to get and always will be. Vito's makes a good 240 package but you can get a bunch more out of their production cylinder and head. It all depends on what you want to do and how much you're willing to spend. If you make the jump to a 240, you're going to have to consider the correct pipe, porting, carb and intake to get the most out of it. The majority of my customers consider the options and just go with the stock cylinder, do the porting and head mod. It's a ton less money and the most bang for your buck. As far as builders go, every builder on this forum is reputable. You can't go wrong no matter who you choose. I've seen, and mapped, every builders Blasters cylinders and you'd be surprised how close all of them are. If I was looking for this kind of work, I would call all of the builders, ask questions, consider price and turnover time (if that's important to you) and make an educated decision from there. Hell, if I wasn't doing this stuff, I'd call Denny. The Vito's cylinder has a straight sleeve that the casting is poured over. No machine work involved. Freak had one spin. I've also seen sleeves from LA Sleeve spin and drop. The sleeves that these companies use are not the same as the ones the OEM companies use. Your OEM Yamaha sleeve can't spin or move. The sides of the sleeve aren't smooth like an aftermarket sleeve. The cylinders are cast around the sleeve ( same as Vito's) but the outside of the sleeve has impressions in it that prevent it from moving. It's my belief that the after market cylinders have the possibility of the sleeves dropping or spinning if the cylinder is exposed to any heat over 280 degrees Fahrenheit. I attribute this to the coefficient of thermal expansion. Your cylinder is made of aluminum and the sleeve is made of a cast iron alloy. Under identically heated atmospheres, the cylinder will expand at twice the rate, and size of the sleeve. When you consider the recommended interference fit of the sleeve to cylinder (.004”) there's not much more than the head holding the sleeve in place. I install sleeves every day and I can tell you that when a cylinder reaches 300 degrees Fahrenheit, that .004” interference fit is reduced to .0005. We can use the same coefficient to remove a damaged or mis-aligned sleeve. Heat that cylinder up to 375 degrees and she'll pop out like a new born. The cylinder needs to be suspended or it will anneal. The pins we install on every sleeve we ship are my insurance policy. I guaranty my sleeve installations for life. Well my life at least. I guarantee them not to move, spin or drop. The pins I use are designed with a Buttress thread. This type of plug ( or Dutchman ) has a thread that pulls the plug into the sleeve and locks the sleeve into place. Once they're in, you're never getting them out and the sleeve will never move. I need to sleep at night and I can tell you I've never had to honor that guarantee in 30 years of dropping sleeves. Whatever you chose to do...........You're an informed buyer.