Review of HKS silencer inserts for Hi-Power exhaust
Review of HKS silencer inserts for Hi-Power exhaust
As many of you know, I'm not a big fan of my HKS Hi Power exhaust due to the drone. I've been fantasizing about buying the HKS silencer inserts for many months, but wasn't very optimistic about them. I expected that they would reduce the sound level, but I also expected that they would reduce the performance by MUCH MORE (20+ HP).
I finally got the gumption to order them last month, and they took a whole month to get here (cardomain.com). They were also a lot more work to install than I expected since the "coffee cans" are nearly impenatrable by a drill. Those suckers melted several of my good bits with a corded hi speed drill.
Anyways ... it didn't start off good, but I datalogged my torque curve with and without them within about half an hour, and I also did videos from outside the car. To my EXTREME surprise, the difference in sound level isn't at all noticeable from the video, but it is very noticeable from inside the car. It has TOTALLY removed my desire to put the stock exhaust back on. The drone is no more!
http://www.youtube.com/watch?v=Zgz-2BuKM0w
Back to the torque curve... it is nearly the same! It ain't worth a second thought!
The yellow and pink lines are the torque with the silencers and the blue is without.
I finally got the gumption to order them last month, and they took a whole month to get here (cardomain.com). They were also a lot more work to install than I expected since the "coffee cans" are nearly impenatrable by a drill. Those suckers melted several of my good bits with a corded hi speed drill.
Anyways ... it didn't start off good, but I datalogged my torque curve with and without them within about half an hour, and I also did videos from outside the car. To my EXTREME surprise, the difference in sound level isn't at all noticeable from the video, but it is very noticeable from inside the car. It has TOTALLY removed my desire to put the stock exhaust back on. The drone is no more!
http://www.youtube.com/watch?v=Zgz-2BuKM0w
Back to the torque curve... it is nearly the same! It ain't worth a second thought!
The yellow and pink lines are the torque with the silencers and the blue is without.
Last edited by Gernby; Aug 3, 2007 at 08:12 PM.
Sweet. Now if you could just get HKS to make some smaller tips to replace the coffee cans on there now, you will be rolling smooth. 
Bravo for being the guinea pig on this one. Glad it didn't remove any power.
Bravo for being the guinea pig on this one. Glad it didn't remove any power.
I'm not going to refer to the tips as "coffee cans" anymore. If they were coffee cans, they would have been easier to drill. I'm now going to call them "depleted uranium pipes".
I'll try to remember to take a picture this evening, but honestly, they are very hard to see when they are installed. The only visible difference is really just the allen headed bolt that holds it in. Depending on where you drill the hole, that won't even be very visible. I drilled mine on the bottom so they would just be visible from some angles, and would be easy to take off.
I'll try to remember to take a picture this evening, but honestly, they are very hard to see when they are installed. The only visible difference is really just the allen headed bolt that holds it in. Depending on where you drill the hole, that won't even be very visible. I drilled mine on the bottom so they would just be visible from some angles, and would be easy to take off.
Lexus Test Driver
Joined: Oct 2006
Posts: 1,170
Likes: 0
From: Dallas, TX
DU isn't so bad. 304 stainless, now that's a whole different egg to crack. I've never seen a drill that lasted in stainless.
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Driver
Joined: Feb 2007
Posts: 137
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From: GA
Very interested in this Gernby, many many thanks for this informative post.
It uses a allen head nut and a bolt to hold the insert in place?
A set of black finished ones might be the most visually appealing.
I would be interested in this "option", especially for long trips where I might actually find the drone objectionable.
Exactly which "insert" do you order. I think there are 5 of them listed.
It uses a allen head nut and a bolt to hold the insert in place?
A set of black finished ones might be the most visually appealing.
I would be interested in this "option", especially for long trips where I might actually find the drone objectionable.
Exactly which "insert" do you order. I think there are 5 of them listed.
Last edited by edwin907; Aug 6, 2007 at 03:45 PM. Reason: question
I ordered 3306RA076. The color isn't an issue since they will be totally blackened with soot in just a few days. The allen head is on the bolt, not the nut (ie. it used an allen wrench). The nut is just a regular old 10mm.
It doesn't quite sit all the way back. I could have installed it all the way back, but decided to drill the hole 3.5" from the tip. I guess I probably could have gone 4" in, but didn't want to deal with the precision.
Track times are way too inconsistant IMO. The testing I did was the best validation I can imagine. I did all 3 runs within 15 minutes of each other on the same piece of road in the same direction starting from the same point at the same speed in the same gear while datalogging rate of accelleration via CAN bus.