Working on my girlfriend's auto 82 242T. It hasn't had much done to it (just turned 100k miles) other than getting a new trans (out of a 93 940 -- very nice tranny). But when we got it a few years ago, we needed to replace the turbo. Being cheap, I put in a 740 water cooled Garrett. The car was not intercooled until recently and she was always scared of me turning up the boost. It had the old OEM gauge in it until tonight -- it tended to run in the middle of "yellow".

I got the VDO gauge that IPD sells (-30 vac/20psi boost) and put 'er in. On the test drive, I was surprised at the low levels. Tell me if this is anywhere near correct:

Idle, in Park: about 10psi vac
Driving in 2nd or 3rd gear and foot off throttle, coasting: 20psi vac
Full throttle from dead stop through all gears: 3psi boost!

Never seemed like the fastest Turbo in the world unless it dropped a gear or two on the freeway and it was at like 5000 rpm. But then what the heck do I know about Turbos, I'm a NA guy.

I also noticed a hiss behind the vent controller, so I'll chase that down. Are the boost gauge and climate controls on the same vac line running into the cabin? Could this be the cause of low reading?

I'll be chasing down any other vac issues tomorrow (in the daylight). Curious what normal vac/boost leves should be during regular driving. Should I turn up the boost till it pings and the turbo glows?! TIA.