BUDGET METHOD: Get a good turbo off of a Buick Grand National.
a turbo from an old Mitsubishi Starion would be excellent choice also (It spools really fast! expect boost around 1800 rpm)

$$$: If you plan to go with a New turbo get a T3 hybrid with a TO4E Compressor wheel. It is basically a Ford style Turbo from the SVO Thunderbird & Mustang. This combination offers a lot of CFM at lower speeds. less noticable lag. (I doubt if you will have much lag with the 6 cylinder.)

Building a custom manifold would be nice. but if you can have a muffler shop make you a custom Y pipe then you got half the battle won. We left the stock exhaust manifolds and and used 2"
pipe to form a "Y" pipe merging to 2-1/4" pipe then routed it to the front of the engine and mounted the turbo (mitsubishi) above the front manifold. (I WISH I HAD PICTURES!)

The Compressor outlet pipe has to go down and under the radiator and back up then to the intake. You will have to make a custom box to cover the air-flow sensor. adding a blow off valve before the airflow sensor plate would help when you back off on the throttle to bleed the excess air.

The mitsu turbo is set to about 6psi.

FUEL ENRICHMENT:
We made a device that plugged into the Fuel Pressure Regulator to make the car run richer under boost.

Never dynoed the car but we did manage to get a 14.6 quarter mile time.

Parts was less than $1000.00,
Labor was less than 3 days.

keep us posted! GOOD LUCK.

__________________
WARNING: Bastard Mercedes Builder/Tuner
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Thanks