HKS Downpipe Review!

[mattjk]

There is no provision for the Donut gasket! What are you
guys doing about flex??? Something is going to break...

Matt

[S-WRX]

I dont understand why people have such biased opinion about HKS downpipe, is it because its so cheap that people prefer expensive ones? I mean I have seen PDE downpipe, and it has the same flat design and its $400 and yet I have not heard people complain about the flat design.
I wont have the money to upgrade turbo and do all the tuning anyways, so I think for mild setup this is a good choice (to me at least since I am broke). Until then, I will tell you how my first impression is with this downpipe with stock boost settings.

[supermarkus]

Originally posted by S-WRX
I dont understand why people have such biased opinion about HKS downpipe, is it because its so cheap that people prefer expensive ones? I mean I have seen PDE downpipe, and it has the same flat design and its $400 and yet I have not heard people complain about the flat design.
I wont have the money to upgrade turbo and do all the tuning anyways, so I think for mild setup this is a good choice (to me at least since I am broke). Until then, I will tell you how my first impression is with this downpipe with stock boost settings.

A bell mouth or separate waste gate supposedly helps smooth the exhaust flow and further reduce back pressure. The stock DP forces the waste gate gases against the flat plate and introduces turbulence. I'm guessing this causes back pressure that results in boost spiking. Correct me if I'm wrong.
The PDE isn't a completely flat flanged pipe, it's slightly ovalized and counts as a bell mouth design. Believe me, if someone made a cheap bell mouth or divorced waste gate, I'd be all over it. But the HKS design is basically what you get with the stock DP, minus cats. Anyone decent muffler shop could probably fab the same kind of DP for cheaper than the HKS.

[gryphon]

Originally posted by supermarkus


I don't know what "most people" you've been talking to but most of the
tuning people I've talked to about DP designs blame inconsistencies in boost
and spiking partially on the design of the stock downpipe exhaust flange.
To say the bellmouth design only makes a difference in the 400 hp range is
totally false as proven by Turbo XS, Cobb, Scoobysport, BPM, Cascade Autosports, hell ask Shiv and he'll probably agree that significant hp/torque and consistency gains can be had from the bell mouth design. Of course he'll probably really push the divorced waste gate design too. I'm really anxious his new system to come out.

Yes, it is nice to have an affordable downpipe available and I hope it works well for those of you that are going to try it out. I just feel that it will not offer the same kinds of benefits that the other designs will. If the bell mouth design didn't offer gains under 400 hp, why would so many tuners incorporate it into their designs for their lower hp applications?

I'm not going to argue at which hp level a bellmouth really starts making a difference. I have heard 400. I haven't seen the "proof" by TurboXS or any of the others. I don't believe that any one of those vendors wants you to buy ONLY the downpipe and not much else

I just don't see paying $200+ of a difference for JUST a bellmouth/twin-dump. That's not a lot of bang-for-the-buck. You see my point? Plus, I am hopefully going to get a twin-dump welded on anyways. If I had the choice, at this price, I would certainly take a bellmouth or twin-dump!

And I think the idea of me ever buying Shiv's downpipe (which I had wanted to begin with) is merely a pipe dream... that thing will probably be hella expensive!

[S-WRX]

That is true what supermarkus said as I have also read a lot of post about bellmouth design, but here in california, I have asked a few muffler shop to make me a downpipe, and most of them quoted me $290 or above, so for $175, this HKS "would" be worth it (depending how my installation goes in 2 weeks).

P.S- PDE is flat design for sure, I have seen it in person @ south coast Subaru

[supermarkus]

Well, then I stand corrected. I was going by what Ian, PDE's builder, was claiming on i-club, that older pictures of a flat flange were outdated and his design is a slightly ovalized bell now.

[Garage Tuning]

I have installed many PDE down pipes. I sell them, and Ian is a friend of mine. It is a bellmouth design. If you were to hold the flange up to the turbo, you would see that the wastegate flapper is behind the open area of the flange. This is what is important. Designs like the HKS pipe do cause spiking. The PDE pipe is expensive because it does not cause a CEL, is 100% stainless steel, and has the most *****en welds I have ever seen.
Kevin
www.pkZero.com
www.BulletProofAutomotive.com

[gryphon]

I haven't gotten any spikes as of yet w/ the HKS dp. I'll keep checking that...

[supermarkus]

Does this mean I stand corrected on my correction? You guys are confusing my little rat brain.

[gryphon]

Originally posted by supermarkus
Does this mean I stand corrected on my correction? You guys are confusing my little rat brain.

Hahah, yep! Just means the correction was incorrect. So it was more like an incorrection

[Garage Tuning]

Actually, I think this means you get to just stand, instead of standing corected, or.... something

[supermarkus]

I think my eyes have just gone crossed.

[Garage Tuning]

word

[S-WRX]

lol

[Verdugo]

Originally posted by gryphon
I haven't gotten any spikes as of yet w/ the HKS dp. I'll keep checking that...

It may well easily be my crappy TurboXS ABC that's causing the spiking. What do you use for boost control, Gryphon?