87 300D Turbo Exhaust Mods

[retmil46]

I've been contemplating some exhaust mods to my 87 300D - basically just to open it up for better flow and possibly better fuel economy. In the past, I've heard that when new with the original trap oxidzer, with the trap ox hollowed out and the shell reinstalled, these cars could see in the high 30's on the highway.

When I bought mine over 2 years ago, the trap ox recall had already been done and it has a conventional cat mid way under the vehicle.

From searching thru the "Exhaust" related threads here and on other forums, it seems the conventional wisdom is, at a minimum, to remove/hollow out the cat and remove the resonator.

The stock muffler is still a question mark with me. If I understand some posts correctly, the particular muffler on the '87 is already a straight-thru affair to begin with - one gent mentioning if you cut off the inlet and outlet pipes, you could look straight thru it. If that's indeed the case, I see no need to replace it - still in excellent shape with no rust. Can anyone confirm/deny this?

Stock 2 1/4" exhaust piping is also in excellent shape - so I don't plan on replacing it for doing a budget mod - unless someone has data that says going to a larger diameter along with removing cat/resonator has some benefits.

2 years ago I had the stock POS Chrysler 4 banger gasser muffler removed from the Jeep CRD diesel and replaced with an Aeroturbine straight-thru muffler - made a big difference in that vehicle. At the time, the gent doing the work asked me if I wanted the cat cut out as well - he stated that NC didn't require a cat on a diesel. Being that it was a brand new '05, still financed and under warranty (which did cover the exhaust back to and including the cat), I passed on that option. But he was apparently right - first time I took that '05 Jeep diesel to get it inspected, as soon as they found out it was a diesel all they did was a basic safety inspection - NC gave an automatic pass to all diesels, no emissions inspection or hookup to computer.

If they don't care about an '05 OBDII diesel, that old '87 probably won't even get a second glance sans cat.

Any ideas and opinions are welcome.