I have been kicking the cat removal around for a while, my question is if the cat is the greatest restricting factor in the current stock system, then how could a stage one effect the performance? the greatest restriction (cat) is still in place so the back pressure on the system remains the same prior to the cat. the photo of the cut headpipe shows how much larger the oval shape section that holds the cat in the pipe is compared to the pipe leading into it, even packed with all that crap the area may be equal.

what would be great is if someone had the ability to measure the backpressure of their system prior to removing the cat and meassure after.

 

With the cat gone and a high flow SE air filter i needed fuel management ran like **** for the 1/4 i drove it. Plugged in the PCV from Fuel Moto and it ran great all i had to do was add a little fuel to the 0 column to stop a decel snapping. Face it the cat has to raise the exhaust temp to burn the bad gases for emissions,it has to be some sort of restriction to do this. The thing turns orange at night just look at your headpipe it's blue and gold which is orange in the night. My bike was way cooler and peppier with it gone and an air filter/fuel management system. The stock 96 is still a weak engine in a bagger got sick of that engine fast.

 

are you saying it ran like **** for a 1/4 mile after removing your cat and adding the air cleaner? Not quite sure why the cat getting hot would cause a restriction. The metals in the cat get hot from the exhuast being expunged from the motor and once they reach a certain temp a catalyst occurs between the harmful gases and the metals.

 

More exhaust gases would certainly pass by the sensors without hitting that plug they call the "cat". More O2 would be picked up in the slightly increased volume simply because it exists in the exhaust gases that are now "rushing" past the sensors. Agreed without an air cleaner upgrade it wouldn't be much, but some none the less. I am taking the OP at face value in his post, and you are assuming an air cleaner addition.I completely agree if pipes and A/C are changed a tuner is definitely needed.

Mark

 

Part of this discussion is flawed in assuming back pressure is bad..I actually helps performance to a point. It was related to me as when the performance upgrades make more power than you are losing by not having some back pressure it becomes a non-issue. (ie: a blower uses some HP to operate but makes more than it uses.)

Mark

 

Mark,

I agree that the engine requires a specific amount of back pressure, i was just questioning that it must be that the breather, the cat, and the muffler from a viewpoint of stock is probably balanced with the cat having a larger throughput than the breather and the muffler or a stage one would not produce better performance when the cat is in place. because if the cat was the bottleneck the other two would not be relevant.

 

Yes, i cut the pipe in half and ground out the cat put a high flow air filter and Night stick on it. ran much better when i put a PCV on it with a map from Fuel Moto. I tried it right off without the PCV for the 1/4 mile and it really felt lean and ran real bad till i put the PCV on. I would say the cat causes more heat than without it and does not have a positive back pressure advantage compared to adding or removing discs in a Supertrapp muffler. As i played around with the discs in the Nightstick as you added them you lost back pressure and lost some low end but gained some up top just as the instructions with the discs said. I just installed a Boarzilla with the quiet baffle on a 120R i put in a couple weeks ago and am very happy now, this is the way they should sell them from the showroom floor. I left the cat in and completely stock till the 1000 mile and it really sucked i don't know how anyone could leave it in

 

You are right, the cat looks like more of an obstacle than it probably is ,and that chamber is considerably larger than just the two pipes..The folks that design these things are a lot smarter than I am, but for some reason I can't leave stuff alone. You know, "if it ain't broke I'll fix it until it is".

Mark

 

You sound like me.....

 

Mark you got it dude, double the diameter and you quadruple the surface area, a catalyst accelarates the chemical reaction ( in this case burning the additional off gases) does not mean it slows down the through put.