*89x2* said:
CKA RACING did something like that w/ his LT4 Collector Ed. Hopefully he will chime in as I know he saved BIG $$$$$$$$$$$$$$$$$$$$
Here is my usual response:
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. You can install the L98 part# on a LT4 using the factory LT4 resonator. Cut about ten inches from the stock resonator and the L98 Y-pipes slips right on snuggly.
This saves you from spending the $400+ they want for the PE resonator section. So this system cost me $835 four years ago.
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.
I'm sure there is some hp/torque gain, but, in the absence of a timing slip or dyno run I'd rather not guess.
