Okay,

I bought megan 3" catback ... i'm going to install on my n/a ka24de for now... will it come right up to downpipe that's already there to were i just have to get a step up flange, or whatever?

 

It should bolt right up to your cat or test pipe. let us know how it sounds a post some pics!! i'm thinking of going with the megan pipe as well.

 

so can I just hollow out the cat, or what? I want there to be lots of air flow... or what test pipe, or high flow cat can people recommend for 3" exhaust?

 

just get any high flow cat

running a test pipe wont be legal

 

I don't care if it's legal... our town is nice, you don't even have to take your car to get it registered or insured... you just call or walk in.. .it's great.

 

This is long-winded, but I am mostly typing this to amuse myself, so feel free to ignore if you like

I see by your sig that the vehicle is normally asperated?

If so, it is a proven fact that N/A's function better with some back-pressure.

The reason this is the case relates to some extremely complicated thermodynamics laws. Basically, because the hot gases are expanding as they leave the header, and these gases want to travel on the walls of the pipe, they require some resistance from the system itself to provide orderly flow.

If turbulance is created in the flow space, the currents collide with each other and are unable to breach the system as quickly as if they had flowed orderly.

A terrible but working example is the ketchup bottle. Take a glass bottle, remove the cap and shake it. The ketchep bangs about chaoticly, some comes out in a disorginized kerblop. Take a modern plastic ketchup bottle with a plastic cap and squeezable sides and give it a hard squeeze. Ketchup flows out of the bottle at good speed in an orderly stream. The force applied on the bottle orginizes the fluid against the restricted oriface and voila. You can shake the glass bottle all you want, but the guy with the plastic(albeit restricted bottle) will pump more ketchup per minute then you could hope for.

This, however is not always true of forced induction setups. The turbine provides order in the way its blades shape the exaust which flows through, as well as provides significantly more pressure. As Corky Bell tells it in his book Maximum Boost, turbos want as little backpressure as possible.

Don't be quick to gut a cat because you think its a restriction, you might need a restriction?

JMB

 

there is a post in the na section dealing with back pressure... and it has a lot of good information on picking an exhaust... my set up im going with dual pipes and dual n1 mufflers... but the pipe size will only be 2.25 inch... that is just my set up... read the post and then make an informed decission...

 

nice, I was going to just leave the cat the way it is... but, i'm asking, will the exhaust bolt up to the stock cat without any modification?

btw, I am going with a turbo setup on the ka24de in a few months. that's why i'm buying this exhaust now.

 

it should go all the way to the cat... that is why it is called a cat back system... i have seen cheap systems be either too long or too short... but the quality ones i have installed have been an almost perfect fit...

 

you will need a cat with a 3" flange on 1 side to match up to your new system, and the stock flange on the other to match up to your down pipe. You can however make a "test pipe", this is just a piece of pipe the is the same length as your cat with the same flanges welded on. The test pipe will then take the place of the old cat.

 

or you can buy my test pipe which im selling for 60 bucks

 

so I have to buy a whole new cat? or is there some sort of adapter I can get? I'd like to leave my stock cat on there will an exhaust shop make something for me?

 

unbolt your old cat and take it to a muffler shop (If possable bring your new cat back system in with you so they can match up a flange). Then they can weld a new flange on to your cat for you. They might have a cheap replacement cat in stock, if so you might as well get a new one.

 

nice. thanks a lot.

 

No worrys