So i have a invidia o2, downpipe, and HKS cat-back, but i have not removed the cat and replaced it with a straight pipe or resonater because of the car's warranty, what exactly will be voided if i change the cat?? and is removing the cat and putting in a resonater make a big difference? in sound?performance? or just leave the stock cat as is. I thought about it and kinda makes no since to have the o2,downpipe,and exhaust if the cat is restricting everything? thanks

also, what is the difference between a test pipe and a resonater??

 

The stock cat is one of the most restrictive parts of the stock exhaust.

 

People run cats on their evos?? I don't believe it

Usually dealers will tell you anything post cat is ok but precat is not

 

so its restricting all the work the o2 and downpipe are doing?

 

Most definitely. Get a 100 cell high-flow. All problems solved, and no new problems

Also, your warranty is already void, you modded your car. Welcome to Mitsubishi.

 

my dealer replaced my transfer case, brembos,and bilsteins already with the o2,downpipe,exhaust,intake, and new bov installed, so they do replace things under warranty for me, im just wondering why the cat would be a good deal.

 

No cat def sounds beefier. Not too obnoxious, but like your car has some ****s.

 

Then you're lucky, Mitsubishi wouldn't. If they replace it with all that stuff, the cat shouldn't make a difference as long as you still have one (ie, high flow).

 

Depends on if you like the smell of exhaust at every stop light. But after switching to E85, it's smells sweet. There's good gains from this and the turbo loves less back pressure, but you do take a risk with smog laws. I've been running catless for three years with zero issues...knock on wood.

 

what about a resonater, what is the difference between the test pipe and a resonater?

 

Test pipe is a straight through piece of pipe with the flange at each end to bolt back to stock exhaust.

Resonated pipe is a resonator with same flange to bolt back up

Resonated pipe are supposed to make the exhaust quieter than a test pipe by shear fact of having a resonator in it.

I went resonated(Megan) as I didn't want noise with baby inside.

 

A test pipe completely replaces the catalytic converter with a hollow pipe just like the rest of your exhaust. It's for "off-road" use only (catch my drift?).

People add resonators to their exhaust systems to lower the noise. Its a little restirction but not as big a restriciton as the stock cat. A resonator will NOT help you pass emissions because its not a cat.

 

so resonater will still make a smell like the test pipe?

 

It all smells the same....I went Megan as well.

 

Emissions = Hi-Flow Cat (Mil-Spec 100 Cell)
Non-Emissions = Resonated Testpipe
Increase in sound and power with both options.