what is the benefit of running a corvette tpi intake over a stock tpi intake, are they physically the same for fit, like a direct replacement? and is there any modifications needing to be done to install one? talking about a '91 SD TPI... getting ready to at least top-half my engine and was considering one of those intakes if the bennies weigh heavy enough in favor of it. staying with stock appearance for the most part, kinda' like 'what you don't know won't hurt you'...

The throttle body, runners, and plenum are exactly the same.

The Corvette lower intake manifold also is very similar. It flows the same so there is no benefit. The difference is the Corvette manifold has the intake bolt pattern of the '86 and older SBC style, as well as it having the EGR port on the back passenger side to get the exhaust gases from the #8 exhaust manifold port.

The only upgrade for the TPI lower intake is from the aftermarket, either the regular SBC one from Edelbrock (they make them all for other people but Edelbrock's is cheaper) or the Scoggin Dickey one for Vortec heads (Edelbrock makes it but Scoggin Dickey sells it cheaper).

If you really want to get crazy with it, check out the sticky post "Quest for a better flowing TPI" in the TPI forum and see what we did with welding and grinding to get my Edelbrock manifold to flow from 260 cfm up to 315 cfm.