kinda of a dumb question but what the hell is this thing on my exhaust manifold? realoem shows it as part of some kind of emissions air pump system, theres a pipe comming off the manifold and somthing mounted on it, and a larger diameter tube going to something round by the firewall pass. side and a vac line that goes towards the intake.

what does it do and what happens when i remove the manifold ?

also if anyone knows where to find a good vac diagram for a 96 328 let me know, the bently doesnt seem to have one, trying to track a possible leak

damn i wish i could have found a decent obd1 bmw

Wanna show us a photo so we can tell or help find figure out what it is.

a photo would help

that connects to your secondary air pump. Its an emmision control device, basically a small electric pump that pumps air into your exhaust after a cold start, its used to light off the catalyst faster.

EDIT: You can disconnect it if you want, but you will get a CEL periodically (on a stock obd2 ECU) because it will fail that monitor.