HKS Silent Hi-Power Modification

Tim M · 13-01-2021, 19:32

Greetings!

We recently purchased a non-running Evo 5 project. We had hoped to use the existing exhaust (Fujitsubo), but corrosion has taken its toll.

We prefer a standard exhaust (non-angled) and quiet due to neighbors/laws.

The HKS Silent Hi Power is our top choice currently, but understand it is not a full 3 inch tip to tip. There is a neck down at some point - possibly at the resonator? We are adding a 3 inch elbow/down pipe and would like to maintain to the rear.

We've read where folks modify this section for full 3 inch - ask if folks could offer an image or instructions on how to accomplish.

Thanks!

thetyrant · 14-01-2021, 16:05

If your not shooting for much over stock power the neckdown wont be a problem

Tim M · 14-01-2021, 17:52

thetyrant: Thanks for the response. Goal is only 400, but hate to be inefficient at 'upgrades.' We aren't even positive where the issue is.

thetyrant · 15-01-2021, 09:47

Quote:

Originally Posted by Tim M

thetyrant: Thanks for the response. Goal is only 400, but hate to be inefficient at 'upgrades.' We aren't even positive where the issue is.

If you want 3" then i would go the magnex 3" from rossport with rolled in tailpipe version if there is still 2 options, the rolled in tip is much quieter than massive slash cut version and makes sensible amount of noise, might need to add another silencer if you want it really quiet as true 3" and oem type quiet is tricky!

D.D.A · 15-01-2021, 16:13

Russ fellows should be able to make what you want

VR-4Squid · 17-01-2021, 01:01

Quote:

Originally Posted by Tim M

thetyrant: Thanks for the response. Goal is only 400, but hate to be inefficient at 'upgrades.' We aren't even positive where the issue is.

The pipe through the centre of the back box is significantly smaller than 3" (likely a significant part of the reason they're so quiet). You couldn't really fix it without replacing the back box altogether.

Tim M · 22-01-2021, 20:31

VR-4Squid: Excellent info! Unfortunate though...nonetheless, quiet is the requirement for the area along with a OEM like install. We ended up ordering the HKS Silent Hi Power system...

Appreciate the comments folks.

j dog · 22-01-2021, 22:58

Quote:

Originally Posted by Tim M

VR-4Squid: Excellent info! Unfortunate though...nonetheless, quiet is the requirement for the area along with a OEM like install. We ended up ordering the HKS Silent Hi Power system...

Appreciate the comments folks.

I had a HKS hi power silent, i can confirm it's very quiet, too quiet infact... it's wrong on an evo!!!

I remember it being 3" but tapering down in parts to 2.75", it's obvious to see where these parts are. Cutting and welding will be required to make it 3" but if I'm honest I'm not sure if it will be worth it. Good luck anyway!

pastymaster · 23-01-2021, 17:53

If you were after quiet then you have ordered a good system. I had mine on a VIII 260 for years and it was quiet.

I'm sure the mid pipe was mild steel which was one of the downsides. It was still a nice exhaust though.

pastymaster · 23-01-2021, 18:44

In fact, on reflection mine wasn't silent it was the Hi-Power. Too many beers!

Wow, the silent really will be quiet!

Phil2333 · 23-01-2021, 19:15

Ive had both the hks hi power 409 and the hks hi power silent

Both nice sounding exhausts..the silent is full stainless and quality..the 409 isnt all stainless and will rust...and curves around the diff which is crap imo

The silent is VERY quiet and a bit restrictive...but still nice

The 409 is louder but not by that much....pity it isnt full stainless

Tim M · 23-01-2021, 21:18

All - appreciate the comments.

Even if unable to 'correct' the sections to 3 inch, a quiet system is a requirement no matter...especially where we live with lots of interested folks (ie neighbors).

Ads9 · 24-01-2021, 15:29

I did this modification to mine, pic of the offending narrow section attached.
If you buy 2 or 3 x 3" stainless flanges and a few gaskets you can weld the flange to the pipe (after you've chopped it) and then use the other flanges to take up the space. I got away without the 2nd flange as my system was off an 8 which is slightly longer than the 9 to start with.
It seems that everyone that's had a HP Silent fitted says they found it too quiet

If buying used make sure the hanger/ fitting kit is included as it mounts very differently to the Super Dragger. Also if your car is lowered within an inch of its life you may struggle as the backbox is 2x the diameter of the Super Dragger.

The main reason for my change was aesthetics, I didn't like the look of the tapered tailpipe.
It is very quiet when driving normally but once you floor it sounds like a jet fighter. I also run a silenced decat with that eliminates the cabin drone when on a long run. Might have a change and pop the HKS back on this summer.

Short vid of the 2 exhausts. I'm running a TTS214b (which sounds horrific when coming on boost) and circa 550hp.

You Tube

anh165 · 27-01-2021, 16:46

The internal diameter of the piping (2.5-3 inch) isn't the limiting factor for top end power - unless you're shooting for 600+HP

I used to insist every exhaust I have must be 3inch or more or I am going to lose performance - I was wrong. I ran 21 psi boost on my DR750 Turbo'd GTO - easily 500+ horses based on how it beat other 450+ hp cars with the stock cat-back 2.75 inch system!

13-01-2021, 19:32	#1
Tim M User Join Date: Nov 2020 Posts: 70	HKS Silent Hi-Power Modification Greetings! We recently purchased a non-running Evo 5 project. We had hoped to use the existing exhaust (Fujitsubo), but corrosion has taken its toll. We prefer a standard exhaust (non-angled) and quiet due to neighbors/laws. The HKS Silent Hi Power is our top choice currently, but understand it is not a full 3 inch tip to tip. There is a neck down at some point - possibly at the resonator? We are adding a 3 inch elbow/down pipe and would like to maintain to the rear. We've read where folks modify this section for full 3 inch - ask if folks could offer an image or instructions on how to accomplish. Thanks!

15-01-2021, 16:13	#5
D.D.A Senior User Join Date: Jan 2006 Location: Staffordshire Posts: 1,629	Russ fellows should be able to make what you want __________________ Need evo

23-01-2021, 17:53	#9
pastymaster North Wales RO Join Date: Dec 2008 Location: Crewe, Cheshire Car: Evo X FQ360, GR Yaris, Fiesta ST, Split Screen VW & Bay Window VW Posts: 4,839	If you were after quiet then you have ordered a good system. I had mine on a VIII 260 for years and it was quiet. I'm sure the mid pipe was mild steel which was one of the downsides. It was still a nice exhaust though. __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

23-01-2021, 18:44	#10
pastymaster North Wales RO Join Date: Dec 2008 Location: Crewe, Cheshire Car: Evo X FQ360, GR Yaris, Fiesta ST, Split Screen VW & Bay Window VW Posts: 4,839	In fact, on reflection mine wasn't silent it was the Hi-Power. Too many beers! Wow, the silent really will be quiet! __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

23-01-2021, 19:15	#11
Phil2333 Tarmac Tyre Shredder Join Date: Dec 2004 Location: North west. Car: Evo 6, Forged 2ltr 8MR engine...405/400 Posts: 14,488	Ive had both the hks hi power 409 and the hks hi power silent Both nice sounding exhausts..the silent is full stainless and quality..the 409 isnt all stainless and will rust...and curves around the diff which is crap imo The silent is VERY quiet and a bit restrictive...but still nice The 409 is louder but not by that much....pity it isnt full stainless __________________ My Evo 6 resto thread... To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

14-01-2021, 16:05	#2
thetyrant Senior User Join Date: Oct 2002 Location: Cumbria.... Car: BMW 130i & MR2 Roadster - Previously: Evo9, Evo5, 2 x Evo2, all gone but not forgotten. Posts: 16,909	If your not shooting for much over stock power the neckdown wont be a problem

14-01-2021, 17:52	#3
Tim M User Join Date: Nov 2020 Posts: 70	thetyrant: Thanks for the response. Goal is only 400, but hate to be inefficient at 'upgrades.' We aren't even positive where the issue is.

22-01-2021, 20:31	#7
Tim M User Join Date: Nov 2020 Posts: 70	VR-4Squid: Excellent info! Unfortunate though...nonetheless, quiet is the requirement for the area along with a OEM like install. We ended up ordering the HKS Silent Hi Power system... Appreciate the comments folks.

23-01-2021, 21:18	#12
Tim M User Join Date: Nov 2020 Posts: 70	All - appreciate the comments. Even if unable to 'correct' the sections to 3 inch, a quiet system is a requirement no matter...especially where we live with lots of interested folks (ie neighbors).

27-01-2021, 16:46	#14
anh165 Registered User Join Date: Jan 2021 Posts: 10	The internal diameter of the piping (2.5-3 inch) isn't the limiting factor for top end power - unless you're shooting for 600+HP I used to insist every exhaust I have must be 3inch or more or I am going to lose performance - I was wrong. I ran 21 psi boost on my DR750 Turbo'd GTO - easily 500+ horses based on how it beat other 450+ hp cars with the stock cat-back 2.75 inch system!

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