The 2003 Z I purchased has its post cat cut off and a haggard crooked welded pipe after the O2 sensor causing some gnarly sounds under load. I am currently running a stock Y-pipe and an S-Tune mid-pipe/muffler. With the cut cats, I managed to still pass smog but the noise it creates (like a gurgling rattling noise from exhaust leaks and the fact the Y-pipe flex joint is about to explode from being twisted onto crooked flanges) I have been considering resonated test pipes instead of buying used OEM cats for $300+ with no guarantee. I have also considered HFC's but after reading on here, it appears if you don't spend $600+ on new HFC's you're not getting quality replacements.

My new plan would be possibly installing a set of resonated test pipes (that may look like they will pass a visual smog check) but worst case, I can install the cobbled up cats if I need another inspection and remove them again. The only downfall I see with test pipes is noise, hence I am HOPING a quality pair won't be to raspy. So far, I am looking at a set of Berk Technology resonated test pipes, any other suggestions?

 

https://www.z1motorsports.com/exhaus...ls-p-5420.html

When I put my AAM test pipes with my S-Tune, it was LOUD. Installed a XYZ with the resonated pipe and now it sounds amazing. Not too loud, but when WOT it screams!

 

he is in commi-fornia.... he is going to have hell with anything that isnt CARB certified, or whatever they call it

 

She* haha, but no worries I "know a guy" and also, the car is mainly used for track. The only downfall, is I drive it to the track which is where I run into possible issues. I'm quite confident the car would be fine with test pipes on a legal note, the car doesn't look fast and furious and I also removed my tint, slapped on a front plate and don't drive like a maniac on the street like all the other people in this state do haha. (knock on wood)

 

if you are not worried about it, then MD xyz pipe or art pipes

 

Just run stock exhaust for inspection then switch it out. I don't know why this is a problem for so many people living in CA.

 

This only becomes an issue if an officer pulls you over and inspects your car, but other than that, yes its easy enough to slap stock parts back on every 2 years if you make it long enough without getting caught.

 

I had the ART pipes installed briefly while I was getting a broken CAT bracket welded back up. They didn't sound bad under normal driving conditions with my Bassani catback system. But under WOT conditions, things got a bit tin-can like. High pitch buzzing coming from the rear mufflers. I wasn't a fan of that.

 

How in the world did you get modified cat's through CA emission testing? Did they not do a physical exam with the mirror-on-the-stick?

I thought a cat can't be modified at all in CA..?

 

Very good question. I put a stock air box on it when I purchased it but when I was under the car I didn't even notice they were cut until I bolted on the new exhaust (had some nasty ebay exhaust on when I bought it) but I sent it to smog anyways so I could register it. I didn't pass the first test because the battery was disconnected and the monitors weren't ready but when I drove around for a half hour and took it back, they scanned it, checked under the hood, and sent it out.

 

Smog testing here, while strict, isn't that detailed some of the time. (Some times though, you'll get someone who doesn't like the way you look or is just overzealous about it and they will look everywhere.)

But, Z33s and most other OBD-II cars are merely scanned at the OBD comm port for anomalies - which the machines can and will pick up. But, obvous modifications like FI and the occasional catalyst if they look under are almost always caught.

But no sniffer or dyno.

And you're right, any mod to a catalyst is verboten here. HFCs, by statute, are 49-state (or less in the case of some states that follow CA emissions stds.)

 

Or why not just gut the stock cat?

 

Wouldn't be that simple, would have to weld in new flanges and new pipe. As stated, the OEM cat has been cut after the O2 sensor and a crooked pipe/flange has been haggardly welded in. The welds look like chicken poop with wire sticking out and with it being crooked, its twisting my y-pipe.

 

Those jacked up cats with crappy welds aren’t going to help your exhaust flow at all.

Do you know what month your Z is Flash? Mine is a early ‘03 and there are a few things they changed just a few months into production.

 

Mine is also an early model, dated 09/02

 

Awesome - Two things off the top of my head:

- The early touring models came with 18x8" wheels front and rear. They changed the rears to 8.5 at some point
- The engine strut bar on the early units came standard with M8 bolts which they later increased to M10. If you decide to go with a Motordyne plenum spacer you will need to tap the mounts to increase the size

I'm sure others will have some input as well. If you're willing to go with aftermarket cats I recommend Fast Intentions RHFC's. Really a superior product.

 

I just installed Berk resonated test pipes. Idk what catback i have since it was from an old owner, but It makes it sound much deeper and and a bit louder under load.

 

Buy Berk pipes and never worry again