SLO C5

I picked up a used set of LG Pro LT with the high-flow cats. I had originally planned to run off-road pipes in their place, then put the cats back in when I have to smog in a year. The cats are tack welded in place instead of using the clamps at one of the connections. Anyway, these are the older generation of the Pros, with the X-pipe before the cats. The new systems have the cats after the collectors, then the X-pipe. Because the off-road pipes that LG sells for $40/pair are 11” long, and the cats I have on my system are 9.5” long, there may be some custom work done to get this to bolt up. The X-pipe/cats/rear pipe assembly is in 1 piece right now, right off of the car they were installed on.

I have the Bullets right now, and was looking forward to my car being ridiculously loud with the LG Pros and no cats. Will the high flow cats really make it that much quieter? I know they aren’t nearly as restrictive as the stock cats, for flow and sound. I’m just wondering if it’s worth it for me to spend the time/money for what may be too loud and for a <5hp gain.

So has anyone gone to from cats to no cats or from no cats to cats with the Pros or any other LT header?

FWIW, I think the Bullets on a non-cammed car are much too quiet for my taste.

TM-Z06

Keep the cats on, there's only a 5-10 hp difference between the two.. With the LT's - those bullets are going to get a lot louder.

Camaroguy22

Cats do quiet a system down a bit. I think your system without cats and the bullets would be incredibly loud.

Switchbarrel

Don't forget the rotten egg stench that comes with no cats...something you'll enjoy everytime you're stopped at a light or idling somewhere.

Last C5

Infineon and Laguna Seca tend to pass cars for sound if they have cats and fail them if they don't. Someone posted that it's about a 6 to 10 decible difference depending on X-pipe or not and the type of cat back used. (All information offered at no cost is worth just about as much)

0euro@EFIAlchemy.com

if properly tuned and the cat saver function is turned off in your pcm you will never have any smells at all.

chiefDave

What?????? O yea that is what I run now, and yes, it is insane but in a good way. Orinal post, all depends on what you like and what you like for the street. Keep out of it and you will be ok, if not, the entire block will hear you coming and going. CATS on LGs make very little delta. Vette did an article a few years ago and the delta was less then 1 RWHP. I have been bother ways and I must say that yes, it does tame it down a bit with cats. With out "Sounds like Godzilla licking his teeth", write that down, CC chiefDave
Dave

SLO C5

I want it very loud. With no cats, LTs, and a big cam I can imagine it's ungoldly loud. Maybe too loud. As I said, the Bullets with cats and stock manifolds are not nearly loud enough for my taste.

Maybe running them with cats is worth a try, they still should be a good bit louder than the 2 pup cats and 2 stock cats with the manifolds.

I wish there was an easy way to quantify loudness, outside of a dB meter that is.

jirasvet

It will be loud with out cats.I run LG LT race setup with tri-flo bullets wish i got random tech cats
If all you do is exhaust system running with out a high flow cat will increase HP, But some high flow cats can increase your lower end torque with out giving HP increase,and if if you care about emissions keep it legal.
Random Tech best high flow converter in my opinion.

One day this will be my ZO6
You want a fat CAM checkout this link:


http://www.metacafe.com/watch/279656/corvette_dyno/

CodeName Z06

What does the cat saver function do? If this actually works to remove the smell no cats it is.
PS i should probably ask the guy that going to tune the car, but i have not foud one yet

jirasvet

cat saver is actually called COT or Conerter Overheat Temp or something like that,
Keeps the car from melting down the converters if they get to hot the COT will richin the fuel mixture,making them stink to keep from overheating and having meltdown of the platinum fillament inside the converter.

Corvette Don

NO cats, I dont have any with mods in sig and love it. PS if you run the car in the garage (yes with the garage door open) after a few mins the smell will annoy you and your clothes will smell like gas.

zeevette

I've run the LG Pros for years without cats, and with the latest round of mods, they became annoyingly loud. With the Corsa Pace car catback I just installed, and the addition of HF cats, I'd say it's about 15% quieter, than w/o. Very nice balance, but not too applicable to your combination.