Well, that was kinda' why I asked the original question. A bigger one has a larger scrubbing area, but does it flow better, worse or the same? And the body size thing for install. I don't think I'm going to get that much of a kick with an NA. I am just replacing it because my emissions for inspections have been passing, but getting rattier. I think the cat might have taken it tough when the UIM went.

The weather has been crappy so I haven't gotten under the car to measure the pipe size and body yet. i'd like to avoid any reducers

...And nobody seems to want to answer it :?

Anybody there???

FWIW, in my searches I never caught any peformance comparisons for the cats. Or complaints on one cat over another. The coventional wisdom just being, get a hi-flow cat. Now if you want to start a holy war.... ask about mufflers. Diverse opinions, but that usually has to do with sound tone. There were some tests. Among the preferred muffs the numbers came up pretty close wthi the Magnaflow flowing (some) better.

Yeah, I've actually got a Magnoflow muffler installed already. I just want some direction on choosing a cat converter, so we'll see if anybody gets to this post later today.

Bueller? Bueller?

Is a small or large cat better on the Bonneville?

Sorry to bring this one back from the dead......

I'm ready to order a converter TODAY. I would like recommendations for cat converter body size. I know the I/O pipe size to buy, but I'm talking body size and internal surface area. Please let me know some of the different models you guys have used!

BTW, the Tech Info article about exhaust is good for choosing a muffler, but there is very little content about cat converters. Perhaps we need to start a thread about proper sizing and matching to cat converters to different sizes of motors.

2.5", 3", 2.25", 2.5", 3", 2.25", 2.5", 3", 2.25", 2.5"2.5", 3", 2.25",, 3", 2.25", 2.5",2.5", 3", 2.25", 3", 2.25",
AAAHHHHHHHH!!!!!
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Anyhooo....

my pipe going into my cat looks alot bigger then 2.5, it looks like 3", and my other pipes look like 2.5"

im going to measure everthing when i get home tonight, so ill post an update then..

Ben, get the smaller body. It'* designed for your car. You want the 2.5" unit and reducers.

I have the smaller unit, same size as the stock Cat, but flows 10% more. I saw Magnaflow data that my exhaust shop has to show this. He also had a cutaway to show HOW it works. It'* just 10% more surface area in the grid. Larger grid surface. Still handles emissions just as efficiently.