I expect your mechanic is talking about the exhaust manifold, not the intake manifold.

And I bet the engine you bought did not come with a turbocharger on it already - your mechanic is probably taking the turbo off your old engine and putting it on the new one.

I understand that the exhaust manifold on the 1990 and newer cars is a more efficient design than found on the 1989 and earlier cars. It's supposedly good for an additional 10 hp. However, I believe that the new flange was designed to fit the smaller Mitsubishi turbos that came in 1990 and newer cars. I bet your car originally came with a larger Garett T3 turbo, which doesn't bolt up to the new design manifold without some machining.

So, your mechanic probably wants to take both your turbo and your exhaust manifold (they are bolted together anyway) from your old engine and put them on your new engine. The bolt pattern is the same to fit both old and new types of exhaust manifold to any year B230FT engine block, so that would be the quickest fix to get your old turbo onto your new engine.

However, maybe your best option is to keep the 1990 engine's exhaust manifold right where it is, and have your mechanic adapt it to fit your Garett T3 turbo from the old engine. It is a fairly easiy job for a machine shop to mill the 1990 or newer exhaust manifold to bolt up to the earlier (and larger) Garett T3 turbo. If you post this question on www.turbobricks.com, several people can reply with their personal experience, adapting the 1990 exhaust manifold to fit a variety of turbochargers.