Will the 86.5 exaust fit my 1982 4.5 liter? I just got my insection today, and you guessed it no more cat test for me in Texas.

 

Yes. The manifols will bolt up, but the rest of the exhause will not. You will need a new y-pipe to hook it up to the rest of your exhaust. I think Motorsport was working one one.
http://www.motorsportincslc.com/

 

Brad;

I have an 86.5 exhaust on my 84 track turd.

If you have the manifolds there will be two issues, w/o there are three.

If using your stock manifolds, a modification is needed at the front of the Y pipe (forget which side, I think passengers) . There are no provisions to hang the intermediate passengers muffler on the car. A hanger will need fabricated (I used banding clamps). And lastly, a RMB is recommended as it will be very tight in front of the battery box for the pass. pipe as a bit of proper placement was needed.

The 85/86 ex. manifolds are more similar to shorty headers and will offer a bit better flow. (I have a few sets for sale BTW)

After dyno'ing my 84 5spd with the 86.5/RMB it showed ~25 more HP over other 84's. YMMV.

 

Not quiet right! Yes the manifolds will bolt up and the cats will almost too. All he has to do is to extend the passanger side flange by a couple inches, the rest of the cat will be a no issue. The problem with the 86.5 cat back section is that it will need some moderate modifications to clear the battery tray. You should look for a '85-'86 system cause the cat back on that system will boltup to the cats withouth any issues at all (they don't interfere with the battery box). The best solution would be to buy a '85-'86 (NOT '86.5) exhaust system. It will only need the passanger side cat flange extension and nothing else.

 

Mostly, I was speaking of the manifold.
Imo000, you are correct about the battery tray. That is why I have decided to stay with single exaust out to the rear.
Thanks for the info.