We may have an answer for you soon! We are in the process of purchasing a '90 190e 2.6 M103 for developing a Twin Turbo kit.
So far we have determined the cost to be under $3500. We will also be doing a 89 300e at the same time. Right now this project is set for May/June 03.

To answer your questions:
1. for 6psi an intercooler is not really needed. It would be nice.
2. We will be making some plug-in mods to the CIS-E. We have run this set up before and it has handled 6 psi.

***If you can provide the turbos you can get a kit from us for under $1500. This would be manifolds (exchanged), Oil lines, CIS Airbox Adapter, Pipes, downpipe, Intake pipe/air filter & CIS-E plug-in black box.

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WARNING: Bastard Mercedes Builder/Tuner
Sorry if I don't answer your email or questions
I don't check here too often.
I am normally on the 190revolution.net board.
Thanks