So I bought a '79 L48 earlier this year, and I'm looking to replace the mickey mouse exhaust I currently have dangling from a small assortment of threads underneath my car. Problem is, like with everything else, there are SOO many ways to spend the money and I'm not sure if side pipes are for me.

I think the Hooker-style side pipes look fantastic, but I'd really like to be able to hear my stereo from time to time. There is also the small matter of the catalytic converter and the ensuing legal concerns. My understanding of federal law is that I cannot actually move the cat to a non-stock location, correct? That means I can't even have true duels, even though dual modern cats would likely be more effective that one antique circa 1979 .

I've heard tell that the reverse-flow baffles are reasonably quiet (for side exhaust), but that they are consequently very restrictive. Any opinions? If I want to hear my radio/carry on a conversation, are side pipes out of the question?

Also, how do modern cars with side exhaust (viper, etc...) deal with the cat requirement? I would assume the cat is inside the pipe somewhere? Is this a setup that can be replicated with a Hooker-style side exhaust, or is it at least conceivable to the point that I could tell the emissions guy that is what is going on? My father says his '77 GMC Jimmy has passed the Utah sniffer test without cats, and I've seen people on the internet (ya, I know. it's the internet) claiming similar things. I believe it is possible to pass my local sniffer test without cats, and if I told the emissions guy I had cats in the side pipes he would probably buy it (there is a reason I go to that shop for inspections )

But, even IF I can pass the sniffer without a cat (or maybe with one in the pipe, who knows...) and get the sticker, would you expect some over-zealous cop to come after me and just assume (logically) that side pipes=illegal? And if they do, what is the penalty for not having a cat/having a non-stock cat?

Thanks in advance,

Kristoffer

EDIT: I knew I'd seen something similar. See HERE for what I'm hoping to do about the cats. Problem is, Hookers/OBX pipes are 4". Not 4.5". And I don't know what the heat from a cat in the header collector would do to the paint...

 

It depends on what state you're in (I think). Here in MD, it's illegal for a shop to remove the cat, but not illegal for the owner to remove it (which is why some shops don't worry about doing it). If the car is registered as historic in MD, it's not subject to any emissions tests or requirements anyways. I own a 79 and it had the original cat that hung below the frame and scraped on speed bumps. It came off when the engine was rebuilt and true duals (without cats) were installed. I know Corvette Central makes true dual exhaust for the later cars (probably just a stock 75 exhaust lol), so that would be where I would start looking

 

In Utah, as you probably know, it depends on which county you live in and normally the inspector wouldnt buy the catalyst in the side pipe story. Have you contacted any local corvette clubs to see what others do?

http://dmv.utah.gov/vehicles-service...ns-inspections

 

I'm definitely in an emissions county, so I have to jump through all those hoops. The car is registered at my parents address in Sandy City (where I lived until last month), and I now live on campus at the University of Utah (SLC). While I've never seen it done on a corvette, there are cars (mostly new ones) that use catalytic converters along with side exhaust.

As mentioned, there are actually cars that have cats in side pipes, so technically speaking it is a possibility. Problem is no one makes bolt-on setups that support that possibility. But, looking at the Cobra linked in my first post, I would imagine a competent shop could build a simple pipe to go over a 4" cat and hook it to an off-the-shelf side exhaust header (hooker, obx, etc...)

I am pretty worried, however, that some over-zealous cop will recognize my car as post-1975 and write me up just for having side exhaust, whether or not I can find a way to incorporate cats. Also, I have heard of laws mandating that the factory location of the cat cannot be altered (ie. my car must always have the stock 2-1-2 exhaust setup). Anyone have info on this?

As for local clubs, I haven't looked any up yet but I definitely will. I would imagine that many people get the Historic/Collector plates, and the corresponding inspection exemptions, but I doubt I could pull that off because I don't have another car to pretend is my daily driver.

Thanks for the feedback,

Kristoffer