Welcome to the Corvette Forums at the Corvette Action Center!


Jan 21, 2001
Philomath, Oregon
I'm going to replace my exhaust system this spring. I've been considering "Power Effects Tunable High Performance Exhaust" system that I've seen in Mid-America. They are kinda spendy and was wondering if anyone out there has installed and used them. They advertise that you can adjust output by 6 positions. If this is just hipe I'll spend my money on other well know brands. Can anyone help?
confused in South Dakota
I running the "Side Effects" Gus, and if I was going to go back under the car with it, I would go with the "Power Effects". Call them and talk to Joe Markovicz, tell him Ken sent you.

_ken :w

P.S., you can see a brochure I scanned for the "Side Effects" in My Garage ;)
Thanks for the info, I'm interested....
I checked out your site and yes the pipes look really nice. Is it really loud? I put pipes out in front of the rear wheels on my 70 1/2 Z28 and it was unbareable. Even back then when I was 21. LOL.
Did it cost you much to get the panels painted to match the car?

Any trouble with driveways?
They are not too loud at all, you can have normal converstion levels while cruising, but when ya step on it, it sure sounds good! :D

It cost me about $150 to have the panels painted. ;)

Oh, and you do have to be careful of driveways when you top the apex, and when you cross speed bumps. You give up about an inch-and-a-half when you install the side exhaust.

_ken :w
power Effects

I bought the power effects about 2 years ago, and they still look really good. I installed them on the car as well. Everything fit togehter really easy and they are built extremely well. It took me longer to jack the car up and remove the old system than it did to put the PE system on. Total it took me about 4 hours I would say. I usually leave them wide open, but on long trips i will close them, and it is not as loud, IMO. I would highly recommend this system and I would definately buy it again. If you have any other question please feel free to ask.. :)

Has anyone seen an independant dyno test of this system against Borla, Corsa, etc? I will have to replace my system in the next year, so might as well collect info now.

Any rust problems? That is what is killing my current system.

I have not have any problems with rust. The customer service at PE is EXCELLENT, and they are very willing to help. As far as dyno numbers I have not seen any. I do know that they showed the flow numbers of the PE system veruses the other brands such as flowmaster, Borla, etc.. and the PE flowed the most, while in the open position. I saw this on their web site. HOpe this helps..

Topless said:
Has anyone seen an independant dyno test of this system against Borla, Corsa, etc?


Visit the site: Power Effects :upthumbs

_ken :w
Thanks Ken.

But, isn't that a little like the fox guarding the hen house? Are they really going to say that someone is better? They might, but how likely is that?

Besides, I have 3" system, so I don't even get representation. :cry

Mike wrote:
"Besides, I have 3" system, so I don't even get representation. "

That may not be a concern Mike; the data that 'Power Effects' posts is flow rate, for the muffler alone. Your exhaust system, of course, is composed of converters, mufflers, pipes, and the connections between them. And what you're really interested in is the total system backpressure. Only about half your system's backpressure comes from the mufflers - restrictive though they are!
Having done extensive study on these systems, I can tell you that the connections between pipe and muffler have a huge influence. For example, on a '90 ZR-1, we got a 20% reduction in the total system backpressure by reducing the system pipe size to 2.25", so there was less disturbance of the flow at each joint, entering and exiting the resonator and entering the mufflers.(Each of these joints goes into a 2.125" muffler or resonator inlet).
I know this is hard to believe; I had some difficulty explaining it to the engineers at GM, some of whom had gone way out on a limb convincing their management that the ZR-1 "needed" the huge pipes. My company was merely offering them a weight reduction along with a cost savings.
My guess, based on the testing we did, was that almost any aftermarket muffler will give you a huge reduction in backpressure, and possibly a noticeable performance improvement, with your only concern being how noisy they are. Some, like the Walker mufflers, are unbearable noisy. Others may well do better.
Redbob- what company do you work for? Have you done testing for an LT1?

I am not opposed to reducing the diameter of the system, I just want to squeeze every hp out of it. Besides, a smaller system will actually fit better with the convertible frame reinforcers. (though the 3" pipes look mean coming up under the rear)

I worked at Calsonic, the current manufacturer of the C5 exhaust system (but not the Z06 system - that's another story!) for a number of years. I had a "responsible" position in Engineering; saying any more would identify me exactly. My work on what eventually became the C5 exhaust system began in 1990, and continued through the launch of the C5, during which time we ran countless noise, flow-rate, and backpressure tests on both C4 and C5 exhaust systems. It wasn't until just before C5 launch that we finally got our hands on an actual C5 mule to do development work; the bulk of our testing was done on C4's, including a number of LT5's. THOSE are wonderful engines!
Anyway, back to your question: I wouldn't hesitate to recommend putting a smaller diameter system (say 2.25") on any Corvette making less than say 450 HP - we developed just such a system for one of the test cars from GM that had a 450 HP Lingenfelter LT5 (there's a car that I'll bet never saw GM's resale lot!) The issue, as I mentioned before, is the size of the muffler and resonator inlet bushings. Since these fittings are so small (about 2.125"), there is an abrupt transition from the larger (2.75" ?) system pipe size down to the muffler inlet, and the pipe has to be necked down to fit inside the muffler bushing, making it smaller still. This sharp transition produces far more flow resistance than does simple frictional resistance in the pipes. And, the disturbance in flow that results when the pipe necks up at for example the resonator outlet (on a ZR-1) produces a similarly sharp increase in flow resistance. Using stock mufflers, you get a smoother transition in and out of each system element, and an overall lower backpressure. A fringe benefit of smaller-diameter pipes is reduced noise and improved sound quality. If you really want to kill the low-frequency 'boom' in a C4, put in an exhaust crossover pipe just before the rear mufflers like the Walker "Rear 'Y'-pipes". We at Calsonic first proved the effectiveness of this crossover. It may be purely coincidence, but one of our engineers went to work at Walker shortly before these "Rear 'Y'-pipes" came on the market.
Backpressure is the enemy here, of course, and its' effect on HP. According to Zoltan Varga, the GM exhaust engineer at the time, the L98 engine could make about another 20 - 25 HP with a reduction in backpressure to the level of the C5 system.
One final note: Having developed the C5 system, and knowing what its' backpressure is, I can tell you that Borla et al are bullsh*tting you when they promise increased HP. Too much of the C5's system backpressure comes from the catalysts for any significant reduction to be possible with muffler changes alone.
Thank you for the info. I know it took a while to type. It is appreciated.

Just bought 86 coupe. Exhaust is straight thru from converters back (no mufflers). Just wondering what effect this has on performance and longevity.
try a dyno test, then you know. As far I know, corsa and B&B are the best in performance increasing. I had a borla at first, but I had no difference in power.
Thanks for the explanation. But now you've perked my curiosity by some fo your remarks...
I have a 92 with true duals, no y-pipe. Now I've been looking at 2 options. 1 is to go with a Corsa cat-back and the other is to just replace those big LT1 mufflers with Magnaflows. I beleive I have a 2.5" exhaust system and have no intentions of increasing hte pipe diameter.
Now if I follow what you are saying going with either of these solutions will not get me any increase in hp/tq. Because the biggest offender is the cats. Correct ???
So if that were the case then would I get a better gain by replacing the cats with ones from say Random Tech that are more free flowing while still meeting emmissions ???
Slightly confused on this ...

So, could I conclude from this discussion that the best bet would be to put a Walker Y-Pipe with PowerEffects tunable exhaust system? I am looking to get closer to the sweet sound of my '69 w/ side pipes. The one goal that I must achieve is the elimination/significant reduction of the resonance (1200 to 1800 rpm) that currently kills the joy of long cruises in our '90, L-98 coupe. The side pipe system looks cool....to bad the cover panels are not available in polished aluminum!

Any suggestions would be appreciated.:upthumbs

Re: Conclusions????

69Crazy said:
...to bad the cover panels are not available in polished aluminum!

Louie, with a little immagination, anything is possible. ;)

_ken :w

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors


MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Advertise with the Corvette Action Center!

Double Your Chances!

Our Partners

Top Bottom