High Flow Cats Vs O/r H Pipe

Bob F

Active Member
May 14, 2015
139
58
38
Roscoe IL
Happy 4th of July! I have been inactive for a while but glad to be back. My 88 GT Vert has BBK shortys, O/R pipe, and when I put on the GT40P heads I had the smog pump and related emissions removed. Now I'm getting a thin coating of exhaust on the paint. On a white car it looks bad, plus it is VERY stinky. Three questions: Is it normal with this combo to get a coating of exhaust on the paint or is it running to rich maybe? If I add just two high flow cats and nothing else will it smell a lot better? With no other emissions stuff will those cats get plugged up easily? Thanks.
 
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I have high flow cats with my current car with all smog equipment. I have had them before with no other smog stuff as well. In both situations the high flow cats eliminated 90% of the exhaust smell. I will never run a catless have pipe in a car again. I simply can't stand the smell.
 
I had an off road H in my 92 and hated the smell so I bought the flowmaster high flow cats from LMR and welded them into my H pipe. I do not have any other smog equipment and even my EGR was bypassed/disabled before I got the car. They seem to be working just fine and almost completely eliminated the horrible smell.

On my 2014 GT I did put in an off road X pipe and while the smell can be a bit much at times I guess the tune is just so much better cause it's not really something that bothers me at all. Kinda funny that my weekend/toy car got cats put on it and I removed them from my daily but it's whatevs.
 
Thanks guys. I ordered the Flowmaster cats from LMR. They get installed this Fri. Sun. I'm going to Byron. With the weight of a GT vert plus the extra weight of the suspension mods and my fat ass in the car I will be around 3600lbs. With 273hp at the wheels (or a little less with the cats) I'm hoping for mid 13's.
 
Thanks guys. I ordered the Flowmaster cats from LMR. They get installed this Fri. Sun. I'm going to Byron. With the weight of a GT vert plus the extra weight of the suspension mods and my fat ass in the car I will be around 3600lbs. With 273hp at the wheels (or a little less with the cats) I'm hoping for mid 13's.
Don't forget some good driving to get you there too!
 
Don't forget some good driving to get you there too!
That's so true on the good driving! I think I am an above average driver. My friend has a 14 Vette with a 7 speed stick and when I drove it he said I shifted way faster and more aggressive then him. The only unknown for me is the drag radials. With the 4.10 and 5 speed it will be tricky.