BerlinaBayRidah

Recently, I started to hear a buzzing/rattling sound from my HKS exhaust when my engine is coming down from high rpm. I took of the exhaust and notice there is something loose in one of the resonators.

I have read in several threads how people have removed the resonators from the HKS. For those of you who don't know, the HKS has 2 resonators. One that is on the piping that connects to the cat and another tube shape one between the mufflers. I have the rattle in the resonator that connects to the cat.

I was planning on going to an exhaust shop and have them fab some straight though piping that would connect the cat to the mufflers. I know this will definately increase the level in noise, but my question is, will I see any increase in performance? Will this hurt my performance?

I am pretty sure those resonators are in place to keep things quiet and definately restrict flow, but is this mod worthwhile and does anyone know about how much something like this should cost to do? Anyone suggestions, opinions, or comments would be appreciated. Thanks.

DrDre1443

i had the resonator removed from my HKS exhaust from my 98 Acura CL. it got alot louder but still sounded pretty nice. Looking back, I would rather keep the resonator. Even though it was quieter, it sounded good. I assume HKS put that resonator there for quiet reasons and to make that cetain sound that HKS exhausts make.

On the performance side, if you have enough air flowing through your system, removing the resonator SHOULD yield a slight bit more power. But you'll never know unless you dyno.

I had mine done at a Midas muffler shop. Cost 45 bucks.

BerlinaBayRidah

The reason I want a shop to fab some pipes to replace the resonators rather then remove them is that I would always have the option of swapping the resonators back on if things got too loud.

I was planning to use fabbed piping for track days.

hygiene boy

here's a modified HKS

BerlinaBayRidah

^^ Thats exactly what I was planning on doing except I was going to have no resonator on the middle piping as well on the fabbed piping.

hygiene boy how does it sound now? Did it get much louder, how's the drone? Did you notice any gains in power?

slalom44

I highly recommend that you do not remove the middle resonator. The resonators essentially break up the length of the exhaust system, which raises the resonant frequency of each section of the exhaust to above redline. They were put there to prevent this resonant frequency from being within the usable RPMs of the engine.

Let's say for example that the resonant frequency of the exhaust system without resonators is at around 4000 RPM. Every time your engine approaches 4000 RPM, the exhaust gets really loud. Below 3700 and above 4300 RPM, it's normal. If you just remove one of the resonators, it will likely lower that resonant frequency to a higher frequency. Remove them both, and expect a very loud exhaust at a certain RPM below 4000 RPM.

I had my exhaust replaced on a car decades ago, and the muffler shop didn't replace the resonator. It hit the resonant frequency at 3000 RPM, which happened to be at the speed limit in fourth gear (4 speed tranny). It was terrible.

BerlinaBayRidah

Other than increasing noise at certain rpm's, would this mod improve performance at all?

This mod will be used for track days only, so I don't really mind if it is loud.

XclusiveAutosports

If this is the case then I would just sell the HKS and buy a single exhaust where you will not only gain more power, but also drop the extra weight.

slalom44

Resonators don't have baffles like mufflers. The air just passes through but the added volume of the resonator does change the tone and the geometry changes the resonant frequency. So you will not see any appreciable gains in performance by removing a resonator.

But the muffler....that's a different story, but you knew that already.

hygiene boy

It's not mine, just a local Florida members. A while back a guy in my area dyno'd stock, then he put on the HKS exhaust and re-dyno'd losing 5 hp/tq. He had the shop guy cut out the resonator and re-weld everything back together. He then lost an additional 5 hp for a grand total of -10 hp.