Well, I was pretty happy with the GMMG behind stock manifolds, Y-pipe, & cat on my LT1, but still wanted a meaner sound...However, after adding the MAC headers with a 12" Dynomax Bullet (basically an offroad pipe) in place of the stock cat, the sound got a lot louder at WOT, but sounded somewhat tinny/raspy in the mid rpm range and kinda lost the "lower" tone it originally had.

So after having the RT highflow cat welded in place of the bullet yesterday, the car now sounds much better IMO. The crappy mid-rpm sound is gone and it now has that typical low rumble LT1's have on acceleration around town and still has that classic muscle car roar at WOT with the GMMG that I've never heard any other system duplicate yet.

I've never liked the sound of no cat(s) on either an LT1/LS1 no matter what "single" exhaust set-up is being used if in conjunction with a Y-pipe due to the rasp & more unrefined sound/tone created. With a "dual" exhaust set-up using an X or H, both motors sound great either way (cats or not) though. Although that's comparing apples to oranges.

But even though I know many will disagree (because everyone likes something different), hopefully this post (example) will help in future searches for those asking between the differences with a highflow cat vs an offroad pipe. And performance loss? I honestly doubt I lost anymore than 2-3rwhp tops since a good highflow catalytic converter has more than proven to hold its own on our cars...

Mike

 

I couldn't agree with you anymore. I just replaced my straight pipe/ cutout combo in favor of my 3 in. hi-flow dynomax cat. I'm not a big fan of the raspy tin can sound either. It just doesn't sound right on single cat cars, JMHO.

 

agreed.. That mid range rpm sound sounds like *** without a Cat..

no power loss either

 

Glad you like the sound!

Just make sure you don't lump all catbacks in the same group. It really does depend on what catback you have, whether or not you will hear rasp. I have the identical setup as you, as we've discussed before, except I have the Hooker catback. You have a completely straight through catback system which lends itself to more rasp. I have used both the high flow cat, and the bullet muffler and neither has ANY rasp, and yes I am very sensitive to that kind of sound. The cat is a bit softer "puffier", but lacks some of the deep tones. The bullet muffler did not add any rasp, popping, or hollow sound, it just made it a little deeper and louder.

ZDriver, I don't agree with you regarding no power loss. A single high flow cat has less flow than even the stock dual cat setup. Removing the cat will add HP, and the more HP you are making, the larger difference it will make. It's purely based on the flow restriction of the cat vs a straight through design. It just depends whether or not the HP loss is worth the sound you are looking for.

I direct you to this article.
http://www.installuniversity.com/ins...n11.122001.htm

Dan

 

Correct me if I am wrong, but you added just one cat? How much the car cost you? Last time I added one high flow cat on my setup from ebay for ~$35, it lasted just 2 months. When I took it off, it was all blown away from inside

 

If you are referring to me, I bought a carsound high flow cat off ebay, yes. My exhaust has been completely converted to a '94-'95 style single cat setup. I had the cat on for about a month, or 1000 miles. It's still in great shape, but I didn't have it on long enough to test it for a long time. I now use a bullet muffler. 2000LS1Z28 and I went completely opposite. I started with a high flow cat, and then went to a bullet muffler. He did the opposite order.

2000LS1Z28 has a Random Tech cat, which are supposed to be the best high flow cat in the industry.

Dan

 

Hi Dan,

Yeah, kinda funny how we tried the opposite thing...You know, I've never actually heard the Hooker cat-back with the bullet in place of the cat, so I guess yours could sound good that way...Although mine clearly sounded worse with the bullet...But I have heard an LT1 with a true "offroad pipe" in place of the cat going through a Hooker cat-back and it was a little raspy in the mid rpms and more higher-pitched overall...And I've never heard another muffler/cat-back that has NOT had even a little rasp with an offroad pipe/Y-pipe set-up. Maybe the bullet works better with a few of them out there, but definitely not on mine and most others...

Anyways, I drove the car again today and it just honestly sounds so much better with the cat back on...And it's staying on this time!

 

Sounds good! literally

Dan

 

Is it possible to buy cats for an ORY and put them on there? I'm getting Jet Hot LT's with their ORY 3" system, and I need to know if I can buy 3" Carsound/Magnaflow cats. Will this work?

 

sorry i didnt write everything i was thinking.. I have 2 high flow cats..

at 2.5in diameter openings they flow appr. 360cfms of air.
2.1 cfms is needed to support 1hp with no power loss...
so if u have 2 2.5in openings ur looking at about 340wrhp with no power loss. anything above it ur looking at around 10% loss..

But most all of us have 3in diameter openings so its closer to 400wrhp support with no power loss.

im drunk right now.. but thats my explanation/

 

Yeah, having two high flow cats helps a ton, and can support a LOT of HP with minimal loss. I'm stuck with one cat after the Y-pipe and even the best highflow 3" cat is going to cost me some HP, even at 300 rwhp. It's not the end of the world though, it just depends on if the cat helps your sound, and if it's worth the HP loss.

Dan

 

Not sure. I think most guys that go with dual cats in the Y-pipe do a custom Y pipe. I bet it sounds great.

Dan

 

Can't you make up some of that loss with cutouts? I hear cutouts work great if you HAVE cats.

 

For sure, but it has to be placed before the cat somehow, and you are not going to want to drive around with the cutout open all the time. It's incredibly loud, and to me it's annoying.

Dan

 

What would happen if it was place after the cats? Would I be better just getting an ORY with the cutout?