Yes , I'm telling you to have a decent exhaust shop fab one up for you.

The 5.5 l V8 (300hp) in your ML should have about the same flow / performance requirements as one of its american counterparts (Corvette, Mustang,etc) a decent exhaust shop can fab one with the proper flow rate and duty cycle for a fraction of the $2k, more like $200 or so.

As long as the shop does a nice install and suspends the exhaust on the rubber hangers as MB does, rather than welding it, I say do it.

I have purchased several cats for R129's this way, even get a certificate for CA emissions when I do it..You'd never know the difference.

You can also buy a "bolt-on" solution. There's a fellow in San Diego who will fab the cat and ship it to you for around $500 or so.. I can dig up his info if need be, but his cat is really no different than what a good shop could make for you...

The ML probably uses three inch exhaust. Shouldn't be a problem matching one up. Just tell them to be careful with your 02 sensors.