lol kasko, if you want to see an example of how 18x9 +27 sits looks for photos of 33's with r34gtr wheels. They will poke 3mm more then those... Itll fit nice IMO
If you want to go 9.5 on the front, you have to go low 20's in offset for inner clearance, so you will get a bit of poke but as the pics on previous pages show it looks tough.
Look at it this way, the difference between 9" and 9.5" is 12.5mm. Therefore in the same offset a wheel that is 9.5" will be 6.25mm wider on each side of the wheel, than a 9"