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Hollow cat performance issue

I know it's illegal, but my 1989 F-250 arrived with a hollow cat. I installed a re-manned 460, and still lacked the power it should have. I was also stalling occasionally from a dead stop. I pulled the old O2 sensor and immediately picked up power and cured stall issue, so I replaced it. Old 02 sensor I think always showed a rich mix and leaned out the engine. I still feel there's more power to gain. Could the hollow cat be responsible due to lower back pressure or another reason?
 
I also have an '87 F-250 with a 460, and there is a significant difference between the two. Are you suggesting that a deleted cat has no effect on o2 sensor readings or air flow?
 
that makes sense. I'll first attempt to restrict air flow through the hollowed cat and see if that helps. If not, I may go ahead and replace it. Thanks.
 

dustybumpers

don't play well w others
Power difference could be rear gearing.

Cat shouldn't matter, but if there is a fuel problem that caused the cat to fail, and the previous owner to gut it, you should fix the problem.
Have you pulled the codes yet?
 

dustybumpers

don't play well w others
replacing the cat without fixing the fuel problem will cause the new cat to fail
 
Any previous issues were resolved with the new engine, and there are no codes. When I deleted the o2 sensor of course I got a code for that. The power issue I believe has to do with air/fuel mixture. I think the decreased back pressure is causing a lean fuel situation. I'll know soon
 

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