Well, so much for my plans to put spacers and springs on... Got a bit dissapointed with Lohen's service level, so I scrapped that. Reached out to couple local tuners, but then felt a bit uneasy using a small shop on a brand new car, so steered back towards wheel upgrade. I know, someone will say I could have installed all the bits myself - trust me I can't
Ordered 18x8 OZ Leggera HLTs in Gloss Black from
www.wheelbasealloys.com. Fabulous service, highly recommended. They called within couple hours of me placing the order to iron out the spec. I ordered 225/40/18 Michelin Pilot Sports to go with the wheels and the first thing we needed to change was tyre profile. 205/40 is factory recommended for 18x7 wheel, so to keep the rolling radius as similar as possible, the 225 tyres on 18x8 wheels need to have 35 profile. Next was the offset and they recommended ET45 to clear the JCW BBK. Btw, if you were to go with the 17 inch Leggeras, the offset would need to be even more aggressive at ET35 according to OZ, due to the shape of the spokes on the inside apparently. I was really impressed by the guy on the phone, he definitely knew what he was talking about. Also he did say that JCW are the most difficult car to fit aftermarket wheels to

So they happen to have a very intimate knowledge of what's required. The only downside was that the Michelin Pilot Sports don't come in 225/35/18. The choice was Bridgestone Potenza, Continental SportContact and Goodyear Eagle. Or I could have pushed the boat out to Michelin Pilot Super Sport, but the chap on the phone said any of the other three will do the job well at lower price - I found that refreshing from him, all I needed was a nudge to spend couple hundred more. One other thing I did spend extra on, was their TPMS sensors, which they'll fit and configure to work with my car.
So the final spec as per below. Will add photos as soon as they arrive
OZ Racing Leggera HLT 18x8 5x112 ET45
Continental SportContact 225/35/18 87W XL