Ok, in the interest of knowledge (and the applied use of knowledge), I am posting a real world 'result' of a product. Hopefully others will do the same with many popular products, by themselves and in combinations.
The catalyst brick in my old 'universal' cat disintegrated about a year ago. So I've been running an 87 GXL (n/a, of course) with a 'test pipe', gutted cat, RB y-pipe, and a pair of Bosal mufflers scavenged from a junkyard Tll. Rather loud and very stinky.

So, in the interests of being a concientious human and also to pass inspection so I can continue to pollute, albeit, minimally, I bought and installed a 'Bonez Superflo Cat'. This is the long one specifically for my car, not the short 'install it in anything' model.

Here are the specifics of my car and the emissions results:
87 GXL (non turbo) 100,7xx miles on fuel injection controls/parts
33,000 miles on Mazda rebuilt motor
Bonez Superflo Cat
RB y-pipe
Bosal mufflers
new plugs with 400 miles on them
new air filter with 400 miles
oil change with filter (Mazda filter and Pennzoil 20w-50)
Emissions results:
Hydrocarbons-0.0178 (standard-0.8000 grams/mile)
Carbon Monoxide-0.0066 (standrad-15.0000 grams/mile)
Oxides of Nitrogen-0.0383 (standard-2.0000 grams/mile)
Carbon Dioxide-49.1861 (no standard-grams/mile)

The car had an ever so slight erratic miss at idle and was probably running a little rich (I get about 200 miles to the tankful with a mix of city and highway driving and a heavy foot).

BTW- this combination has a very nice tone, is quiet, and has not affected power in any noticeable way. I suspect the gutted cat introduced some turbulence that made up for the lack of restriction. If anything, there is a little bit more low end torque, which I would attribute to a slight increase in backpressure. Hard to say really.

 

Yes, I would agree with those results. With my Bonez cat I passed PA emissions with about the same readings, even a bit lower I think. Also there was a noticabe power gain with the system. I have been using the cats for over 2 years now, and still are holding up wonderfully...

 

I am thinking about installing one of these on my 1990 NA GTU. What do you do with the preconvertor?

Scott S

 

you replace it with a downpipe!



you will still pass emission...just make sure your engine is nice and warm...

 

throw it out .

actually i guess that depends on what kind of piping you got with the bonez, but i would imagine most people just run it solo.

 

The bonez superflo replaces the useless precats with a nice downpipe silencing unit.

It sounded great on my NA and I passed AZ dyno emissions without a problem.

Now that I have a turbo it's sitting on the side of my house and I have a RB DP and presilencer.

 

Yeah the superflow is a great product, and i loved the results. My only regret is that if i thought ahead i would have gotten just the hi flow converter. That's because if the time came and i wanted to add a RB header, then i wouldn't need to buy another cat. and would just need a connecting pipe from the header to the cat.

If you are going to buy a Bonez cat (IMO, it's definately worth looking into), and are thinking down the road you want a header too, then get just the main cat. You can then continue to use it when you get the header.