Factory Exhaust Resonator Removal and Free Flowing Alternatives

[SteelBlueZR1]

How many of you have tried keeping your stock 2.75" factory ZR1 exhaust system and just replacing the 1990-92 restrictive resonator with an aftermarket freer flowing resonator or x pipe?

Haibeck says the stock resonator is a major exhaust flow restriction costing about 20hp, due to the resonator core reducing to 1 5/8” ID.

What is the best product to replace the resonator with to maintain the low noise and no resonance I currently enjoy?

I prefer not to go to a straight pipe or crossover, but rather find a replacement resonator with straight through 2.5-3" pipes. Has anyone tried the DynoMax® Ultra Flo™ X performance stainless steel mufflers with 3-in. diameter internal X-pipe balance tubes?

I am concerned about fitment issues, so what have you tried that fits the factory pipes and doesn't drone?

[GOLDCYLON]

Originally Posted by SteelBlueZR1

How many of you have tried keeping your stock 2.75" factory ZR1 exhaust system and just replacing the 1990-92 restrictive resonator with an aftermarket freer flowing resonator or x pipe?

Haibeck says the stock resonator is a major exhaust flow restriction costing about 20hp, due to the resonator core reducing to 1 5/8” ID.

What is the best product to replace the resonator with to maintain the low noise and no resonance I currently enjoy?

I prefer not to go to a straight pipe or crossover, but rather find a replacement resonator with straight through 2.5-3" pipes. Has anyone tried the DynoMax® Ultra Flo™ X performance stainless steel mufflers with 3-in. diameter internal X-pipe balance tubes?

I am concerned about fitment issues, so what have you tried that fits the factory pipes and doesn't drone?

Well you could use a Corsa resonator. The xpipe would be better flowing but you will pick up resonance

[mike100]

Originally Posted by GOLDCYLON

Well you could use a Corsa resonator. The xpipe would be better flowing but you will pick up resonance

stock muffs are quiet even without the factory resonator. There might be a slight bit more rumble, but rest assured that you won't feel fatigued on the highway after a long run at 70 mph.

I would easily say that my stock 90 pipes and mufflers with the magnaflow x-pipe are quieter than Corsa at pretty much every power level.

I used the magnaflow x-pipe from their x-pipe and resonator combo- just hacked off the chrome resonator can due to ground clearance concerns.

[GOLDCYLON]

Originally Posted by mike100

stock muffs are quiet even without the factory resonator. There might be a slight bit more rumble, but rest assured that you won't feel fatigued on the highway after a long run at 70 mph.

I would easily say that my stock 90 pipes and mufflers with the magnaflow x-pipe are quieter than Corsa at pretty much every power level.

I used the magnaflow x-pipe from their x-pipe and resonator combo- just hacked off the chrome resonator can due to ground clearance concerns.

Having all three exhaust systems I would have to disagree with that assessment. However in the end Bert can make up his own mind as it will cost him to try systems out.

[Gunny]

AFAIK there are only 2 systems that have NO drone ... stock and Corsa ... the fitment is fine on either system. Corsa is reasonably tame until you get above 2500-2800 rpm then it is very loud (at least to me).

The early (90-92) stock systems were not only restrictive at the resonator but also at the mufflers ... can't remember the neck down at the muffs but I believe it was about 2" or less. Also, I think that only one tip flowed; the other was for appearance. The later stock systems were less restrictive and if you want to stay with a stock system it's probably easier to get one than try to mod or adapt an early model to fit your needs; otherwise you're looking at a variety of 3rd party exhaust systems. Finding the "perfect" exhaust system for all situations is a tough, perhaps impossible task ... I know since I currently have 3 systems hanging on the garage wall plus a Corsa system currently installed. Every system I have (except for the stock 90) has a certain appeal to me but also some drawbacks ... I'm looking for the happy medium which may not exist.

Do a search on this forum ... the guys in Chicago are doing some really nice things with larger systems, C6 flapper mufflers, etc. I haven't heard any of these systems yet but plan to next week at BG ... great place to hear a lot of different exhaust systems.

George

[efnfast]

I'm running a brand new OBX system, headers and exhaust. No drone. If you're coming to BG, you are welcome to come for a ride with me and listen. Maybe you can drive, maybe.

[secondchance]

Originally Posted by efnfast

I'm running a brand new OBX system, headers and exhaust. No drone. If you're coming to BG, you are welcome to come for a ride with me and listen. Maybe you can drive, maybe.

Agree 100%. I am also running OBX headers and exhaust - completely happy w/ the result.

Bert - if you want you can try my car next time we meet. Any custom conversion you do removing resonator or switching to other resonators will cost at least $100-200. OBX exhaust can be had for $350.
One more thing. Factory exhaust is 2.75" system. However, depending on the year 2.75" pipe reduces by 1/2" or so at transitions to resonators and mufflers - not a true 2.75" system.

[secondchance]

Sorry Bert. Didn't realize you already bought LT4 setup.
Offer to have you drive my car still stands.

[SteelBlueZR1]

Thanks for all the feedback guys. I would love to hear the new OBX system... But I really had my heart set on finding a replacement resonator for the stock 1991 exhaust. The 1991 mufflers according to Chevy are 40% larger than the 1990's and have much less backpressure, plus I like em quiet.

[GOLDCYLON]

Originally Posted by SteelBlueZR1

Thanks for all the feedback guys. I would love to hear the new OBX system... But I really had my heart set on finding a replacement resonator for the stock 1991 exhaust. The 1991 mufflers according to Chevy are 40% larger than the 1990's and have much less backpressure, plus I like em quiet.

I have a corsa resonator in my attic. If you want to get it fit at a shop to try it out. I paid $200 for it I would let it go at that plus shipping.