yes its been done...people "bellmouth" it. power gains, not sure, but certainly puts less stess on the turbo pushing air through there. Its probably one of those things worth a tenth or two. They all add up after awile. Of course the most common is a upgraded higher flowing pump. Alki injection from my experience is amazing. I can end a run with MATs 20+ degrees lower than I started...usually ending a run in the low to mid 50's...40's sometimes. This is with stock IC and upgraded pump only.