this weds im having my flowmaster super 44 put on my gibson dual swept side exhaust, the flowmaster is a 3 inch inlet/2.5 inch outlet. I want to put on some high flow cats, which size inlet/outlet should i get and how many high flow cats should i get? thanks again guys

 

Save your money. The stock cats flow well.

 

with that flowmaster its not gonna matter. the stock cats are pretty high flow, that flowmaster is just slowing down that flow.

go with wide open performance from Magnaflow.

 

would the high flow cats help with the sound?

 

not to get off subject a lil bit, but i seen in your profile that you got 4 wheel disc brakes , i would like the same on my truck, where u get your discs?











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Your stock cats will do just fine, if you want the best quality of sound, you will have to run no cats, not sure if you can in your state

 

nope

 

The cars that need high flows are from around pre 99. Save your money.

 

Wouldn't running no cat turn on your check engine light?

 

no, you can get an adapter for the o2's that will make it go away. Your rear cat reads that there is more air flow and throws the light saying that there is a problem with the cat.

 

Ok, so if you did not buy the adapter thing then it would through a code right?

 

The cat dosent read anything. The oxygen sensors do the 'reading'. The ECU looks at the signal coming from the AFR signal in front of the converter and compares it to the signal from behind the converter. The AFR for the rearward sensor should be a higher value due to the fact the catalyst is there. If you want to remove your converter you will be reducing back pressure and losing less torque during the exhaust stroke. To fool the rear sensor into thinking you have a cat simply use 2 spark plug defoulers in series and screw the sensor into those. This will prevent your ECU from detecting the cat is missing and you will not throw a code. The big benefit from this mod is not back pressure, it is that you can safely advance your timing more than if you had a cat and also run a leaner mixture without worrying about knock.. To take advantage of this you must retune your ECU, no if ands or butts.

 

I think he meant O2 sensor not the actual cat.

 

it doesnt matter what the computer reads, most of those states do a sniff test if i remember correctly.

also from what i can tell exhaust size, shape, and bends effect sound the most.

 

I am glad Indiana doesn't because I know some of my previous vehicles would not have passd. So how does it go? The more bends the ..... it is? The bigger it is the ..... it is?

 

If the vehicle is OBD2 equipt then it will be done via computer test. As far as I hear, only CA may use a sniffer test.

The whole idea of going to OBD2 in 1996 was to make emissions testing easier. I had my truck tested a few months ago, the test was 100% computer and took less time than the drive in at mcdonalds.

My car also passes, and no - I don't have a cat. No codes = pass.

 

im sure it varies per state, all i know is Indiana doesnt care one bit about emissions, unless its visually smoking.

 

I'm in the evo-forums all the time, where probably 50% of the population is cat-less. I think there would be more b!tching and moaning if this was the case. Remember we are talking about post-obd2 here (1996 and up).

I don't even think anyone makes a bolt-on midpipe for the ranger. Most sportscars have them available for "offroad" use only on various websites. You'd have to put something together yourself. Seems like alot of work for someone who's just doing it for sound.

Remember that converters are only useful when the AFR is somewhat close to stoich. When you floor it in your truck the engine is heavily loaded and the ECU goes to a much richer tune. In this stage, your cat is basically doing nothing. This is why sometimes I use a tailpipe sniffer when I tune a car that still has a converter - all the adjustments are made to the WOT map, not the cruising map. (openloop vs closed) - The point of this is that you will get some "smoking" when you floor it because its richer on purpose. The ECU isn't even considering this operation because the oxygen sensors arent even being paid attention too, it only uses the sensors on the front side of the system.

 

well im hear to tell ya, been there, kinda tried it. sounds like crap, runs like it too.

I am running 2 high flow magnaflow cats one per bank and it runs pretty good but not worth the cost IMO.