I’m running 13’s on my 998 it’s quite nippy for the engine size and is fine keeping up with modern day traffic.
The only mod I’m running is a stage 1 kit, it pulls away nicely at traffic lights and will cruise all day at 70mph.
I think you’ve been told a load of twoddle and in my opinion wheel size is irrelevant to engine size.
That's the answer I was looking for! Many thanks