I put a vaccuum gauge on the manifold vaccuum and set the brakes and loaded the motor. the vaccuum went from 18 to about 10. does this mean its getting plugged up? also my cat has flanges on both sides. is this easy to replace myself. the cutting and re weld of air tube I know about, anything else? Also any recommendations what kind and where to purchase new one. I dont have headers, and I have a Flowmaster exhaust.

 

That drop in vacuum is the classic sign of an exhaust restriction, yes, but are you getting any poor performance under load or at high speeds?

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88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

 

Hi Dave, if you want to get a converter, get a Catco Cat from Summit Racing. I recently bought two for my car. I can drop you off a catalog Thursday or Friday if you want.

 

Hey Ray, that would be great. I m not sure about performance since I only had the car for two months but it seems it could be better.

 

I took the old cat out this weekend and found out there was nothing in it. just a straight tube. I guess the restriction wasnt in there. It had the words Car Sound on it. I think its pretty obvious this was not a smog legal cat. I went ahead and installed the the new Catco from Summit. My exhaust is a little quieter now. As far as I can tell I have the stock muffler. there is a GM and what looks like a gm part number on it. Could it be plugged?