I'm not expecting the motor to magically run like a funny car motor, I do however expect it to be able to turn up the specified and expected revolutions.

Probably fresh cats will do wonders for uncorking it, and IMO why use two cats when I can use one large free flow unit und upsize the entire exhaust?

I have to have a cat to pass emissions in my area.

My new motor will have a good 50 more hp and considerably more torque than the current 3.9.

I comprehend the limitations of the ports and valves, no argument that it is not going to make big power. It ain't rocket science. This motor is a good runner, albeit maybe a little tired, definitely corked.

I've just been slowly and steadily bringing this old rig back to life, it's come a long way since I rescued it from certain scrappage...so far it's proven dependable ( a little quirky of course), now its time to upgrade it to be a decent performer all around..

 

I have the Heddman headers that I've been meaning to install but haven't gotten around to it. My initial thought was to simply cut out the cats but the headers were so cheap (just under $200 from Summit) I figured the labor was worth that much. I'm hoping to see basically this type of improvement. As the OP pointed out, I'm not expecting a funny car engine all of the sudden, just a reasonable improvement.

cheers.