i am cuting the 1st cat off and running duals out the back...the air tube that goes into it i have no clue what it does but can u just plug it or should i run it into a pipe?
i have heard u can just plug it up but will that effect anything?
thanks [talking about my 89 here]

 

i stuck a wine cork in mine and used a hose clamp to tighten it down

then i drank the wine

=)

that was several years ago btw. no problems so far. There should be a bypass valve or something. When yuo plug the air tube, the smog pump just pumps outside air back outside...woohoo inefficiency

 

I think the '89 is similar to my 91 and there are two sets of tubes running into cats. Just off the exhaust manifold is the EGR tube which can be plugged, but will probably cause the CEL to go off.

In front of cat #2 is the smog pump line. Mine has a bolt tacked in where the tube rusted out. Still getting slightly better than 15mpg with this setup, so there aren't any adverse performance effects.


I like Torx's idea better. No wine for just putting a stupid bolt in.

 

lol its all about usin what you got!