I've read many threads about people having popping sounds when the car is idling or on decel. but what about when you turn off the car? When I shut the car off, it sounds like the cat or something is making popcorn under the car. I only started hearing this recently. Anybody else have the same thing?

 

Your cat can make popcorn?

 

Hells yeah, fill from the mouth, heat, then watch the fun. Sounds like it's coming from the catalytic converter but can't say for sure.

 

Mine did that. I replaced the main cat and gutted the pre cats. Problem solved, power regained, MPG regained, sounds awesome!! The old cats were burned up pretty bad and crumbling apart inside. That can cause heat to build up in the manifold etc.

 

Did gutting the other two cats affect emissions though? I'm required to do smog test at the end of this year so if it does I might have to replace all 3 I guess?

 

I don't need emissions. I've been told that if your car is running well all you need is the main cat in good shape. Replacing all 3 could cost you an arm and a leg. If it passes emissions with the cats you already have just put them aside and throw on an RB exhaust for what 3 new OEM cats will cost. When it comes time to smog it, swap the factory cats you put aside back on.

It only takes about an hour to swap out an exhaust if you know what your doing and you have the right tools.

 

 

If emissions isn't a problem where you're at, why did you decide to only gut two and replace the main cat NCross? No popcorn for kitty!

 

Back pressure, keep the noise down, keep fireballs at bay, auxiliary ports.

A straight piped rotary is ungodly loud and shoots fireballs.

 

Same reasons why I wanted to keep mine stock. So anyone know if gutting the two cats and replacing the main cat will still be able to pass smog in Cali?

 

Works on FBs, dont see why it wouldnt on an FC.

 

I guess I'll give it a shot next time I'm under the car. And if I dont pass smog I hate you....jk lol Where did you get your new main cat at NCross?

 

O'Reilleys I think. Any old car part store should have one in stock. I just got the cheap $70 universal one because I didn't need it for emissions. Just sound, back pressure, anti fire ball. Not sure how effective on emissions it really is. They have a $300 OEM replacement though.

Just take it to a muffler shop. They should be able to hook you up and weld you in 3 replacements for a decent price.