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I just got a 75mm single hks cat back and it's drones quite a bit. I read a test pipe will cut the drone but add rasp. I've been looking at the apexi active silencer, as well as the the apexi butterfly valve. What about a high flow cat?I can't justify 200+ for a hfc so I planned on removing half of the honeycomb material in the stock cat. Will that make any difference? Any other suggestions? Thanks for any advice
I have the HKS with a Berk 70mm HFC. Drone is horrible. I fell for the 'it isn't that bad' stuff you read on here...wrong. Luckily its mostly a track car now and has only done about 1000 miles in the last few years.
I have thought about a test pipe but the rasp doesn't appeal to me. The HKS sounds so good with a cat. You could always pick one up and if you don't like it you should be able to sell one easily. Also I think people have added a 3 inch Vibrant resonator in place of the one on there to try and help, but honestly my thought is if its too noisy...get a different exhaust. If I drove my car even on the weekends I would run something else or even think about going back to stock. The stock system is just so damn heavy though.
Drone is a relative thing, so if the HKS is bothering you, really the best option is another exhaust. If you're considering gutting a stock cat, a cheaper option may just get a test pipe. If you ever need the cat back, they're expensive.
The drone isn't as bad as I thought it was going to be. I do mostly highway and it's great on a steady throttle I barely hear a hum. It's decal and accel that bother me. True there easy to sell. I will try a test pipe and hfc out to see which I prefer. The apexi butterfly valve is tempting as well. What different did you notice with a hfc over oem cat? Louder, more or less drone? ... Etc
My HKS Single is a love & hate relationship. For track days, autocross, mountain trips, and top down driving it's fantastic.
With the soft top up the 3000-3800 rpm drone is head banging. With my OEM hardtop on it does help some but not a ton.
Anything over a 2 hour drive on the highway is just not doable. I have been considering having a spare OEM pipe turned into a mid-pipe for it however I did come across this exhaust on Facebook
It's linked here
Basically you can remove the Helmholtz or block it off using a 2 plates. I absolutely love the idea but the pipe diameter is only 2.5" the weight is also not the lightest however users seem to say it's quiet as stock in normal form and then similar to the HKS when in loud mode.
@noodels because of that thread a few years ago I had converted a old muffler canister into a side branched helmholtz resonator. I'd say it worked very well, interior drone decreased significantly, exterior noise still solid and audible, now my NVH issues is from solid mounts, bushings, diff carrier etc. and wind noise more than anything. The exhaust sound itself is more clear and crisp but because of the NVH i don't hear it too much unless I have noise cancelling headphones aiding in hearing isolations.
10-03-2014, 02:38 AM
Reduce drone on 75mm hks single advice
