I've heard about them over and over. Could someone please tell me exactly what they are and what they do and if they are worth the money that they cost? Thanx. :cheers:

 

A catback system replaces everything from the main catalytic converter back. Is it worth it? Too many, yes. To me, no. The majority of the exhaust restriction is in front of the converter, not behind. Bolt on some Flowmasters and gut the converter and you'll get good sound and a gain in performance. Save the expense of the mandrel bent tubing for those trying to shave extra 10ths off their 1/4 mile. For me the money needed for a good cat-back system could be better spent elsewhere.

 

Worth the money? You'll need to determine that on your own. Here are some comments I made on a different post. I'm lazy tonight and don't feel like editing it to remove the info that does nopt apply to this post. :D
Before I go on, I'd like to give you some advice. Go to as many vette shows/events and listen to the different exhaust sound first hand. Also take a ride in these vettes if you can to check for resonance. Make sure you ask if any other exhaust mods were done such as headers, cats removed, etc. These mods affect how much resonance there is. From there decide on which look you prefer and also how much you are willing to spend. Also ask yourself what benefits are important to you from the exhaust mods. What's more important? More power? Just a nice sound?
Least costly?

I will make comments on sound and looks. Keep in mind this is based on personal choice. The other comments are base on my five years of reading forum comments, magazine article and personal experience.

Since you mention Borla, I'll start there. This system has been very well known for bad resonance. Wimpy tailpipes for an after market system. Nice finish. Fair price. Sound is ok. Fit is not always the greatest.

Corsa - Practically no resonance at all. Fair price. Good quality. Decent tailpipes. Ugly welds show too much. Sound is ok but not deep enough. Too quite at idle. Excellent fit.

Power Effects - Excellent quality. Nice deep big block sound. Excellent finish. Excellent fit. Have adjustable flaps in the mufflers that can be used to adjust the backpressure and loudness. It also helps in dealing with the resonance. With closed flaps there is a tiny bit of resonance at around 2,000rpm. This cat back is 2 3/4 inch which ideal for torq and horsepower for a streetcar.

B&B Triflow - The best-looking tailpipes around. Excellent quality. There have been issues with fit. Mufflers spinning, not the easiest to install. Comes in 3-inch pipe. The system has resonance.

Flowmaster - Not one of the best-looking mufflers out there for a vette. For some it's just fine and serves there needs just fine. Finish is not as good as the others. Has resonance.

MagnaFlow - Nice tailpipes. Has resonance.

Dynomax - Sound is ok but not loud enough for most. Cheap in price. Lousy tailpipes.

The following info was taken from an article in Corvette Fever June 1998 issue.
Exhaust shoot out! By Jim Van Dorn
Dyno results on stock Grand Sport LT4.

HP/TORQ
Stock:
299/307

BB Triflow catback 3-inch:
310/310

Dynomax mufflers only:
304/310

Borla Corvette Challenge cat back 2 3/4 inch:
304/309

Flowmaster cat back 2 1/2 inch:
306/309

Power Effects cat back 2 3/4 inch:
299/308 - flaps in closed position
311/313 - flaps in open position

As you can see the is very little difference between them all especially when you consider cost.

Some interesting comments they had were, "Borla teamed with Doug Rippie Motosports in developing their Corvette Challenge cat-back 2 3/4 inch system. Rippie's original request for the larger-diameter pipe was made when he fitted his mega-horsepower former Lemans engine (600+hp) to a production ZR-1. Rippie later related, "We found the 3-inch system was great for horsepower, but (it) lost torque. The 2 3/4 inch system was the best of both worlds.

I have an issue with the above. If that's true why is it the Triflow 3-inch tested pushed 310 torq and the Borla pushed 309torq. Could it be that they are really referring to how the max torq moves to a lower rpm with the 2 3/4 and moves up higher in the rpm's for the 3-inch? Is this possible?
I can feel a difference in low-end torq if I closed the flaps on my PE system. Feels like it has more but maybe it's just available sooner.


They also tested sound levels at 70mph cruise, at idle, interior sound. Let me know if this interest anyone and I’ll start a new post with the results. What's interesting is that they don't mention resonance at all. I'm thinking the Cruise @70mph sound level test would be as good indication of how loud the resonance is.
Stock 94
Triflow 107
Dynomax 96
Borla 100
Flowmaster 97
Power Effects 100(Closed) 103(Open)<this turns it into a straight pipe, you can see inside the exhaust.

107 DB is loud for most folks.
For me open headers use to be not loud enough.

So bigger is better for horsepower in a modified car I would think. When you have such a high level of power I don't think it makes much difference if you lose let's say 10-20ft pounds of torq for a streetcar.

 

Take a look at the piper from the cat to your mufflers and then consider a 2 1/2"or 3" set of pipes with smooth bends. That is what a good cat-back brings along with a set of hi-flow mufflers

Then take a look at the front Y with the two pre-cats and waffle bends in the pipes. Again think of a 2 1/2" pipe with smooth bends.

The results of these two upgrades (along with a hi-flow cat) are on my site; and yes it was well worth it to me. Both sound quality and performance took a nice step upward. She now sounds like a Corvette and has performance to back it up.

 

I think headers with a good set of high flow mufflers on the stock rear Y are good enough. I'm probably in the minority on this but I'd rather spend the money saved on a new intake. MUCH more gain to be had there than on mandrel rear Y pipe IMO