Turbo inlet piping size

[Canadian_CD9A]

Does anyone have any experience in regards to running an intake inlet pipe that is smaller than the turbo inlet? I know it's an unusual question because it's so easy to just use a bigger intake pipe. However, I'm after an airbox solution that takes air from the Evo 123 hood, as well as behind the headlight. A company just released a WRC-style airbox with 80mm pipe coupling (3.15") that does this, but it's slightly smaller than the 3.5" inlet on my turbocharger. How adverse would it be to neck down the turbo inlet from 3.5" to 3.15"?

 

[dustyboner]

i wouldn't do it. you want to minimize restriction on the inlet side of the turbo as much as possible. if you want to spend the time, you can calculate the filter and intake pipe restriction, turbo pressure ratio and then check it against the compressor map for your turbo.
Which isn't that easy for most of us to do but there are calculators for all that stuff online.