[Bobboloo]

Thanks for the replies.
I had similar thoughts on the 38mm chokes. They were suggested by Richard Parr when I initially built it as a 3.5L with stock Carrera cams. It ran great but I never had a chance to check AFR's before the owner decided he wanted to go twin plug and that presented the opportunity to go with the Mod S cam since Mahle makes a P+C set for twin plug that allows for a cam with overlap. The owner loves the torque curve with the Mod S cam. It fits for him and I must say I really like it too.
I was hoping there might be an adjustment with air correction I might do before buying another set of chokes.

@ icarp Regarding the 14:1 AFR at 4000. I should have mentioned, this is a street engine. 14:1 is lamda and the owner won't be cruising at 4k or above. Only brief excursions above 4k so I don't see it as an issue.