If you dont plan on moving up to bigger turbos then the HKS downpipe should be fine. The HKS downpipe does not have a bellmouth design.

 

I have it on my car right now and it does the job like scoobysnacks said it doesn't have a full bell mouth designs so that about it. I've also heard that the HKS one uses the same design piping as the pde one with the exception that its one full pipe and not 2 pipes joined together (who knows if this is true...)

As far as performance goes it's OK.. you will have a 50-50 chance of getting a CEL so if you plan on purchasing this inexpensive (thats why i bought it... it's cheap!) you might start looking in to purchasing a MIL Eliminator.

Also you might want to look at what type of cat back system your planing to get (if you decide on that).

I own both the HKS downpipe and the Blitz Nur Spec catback exhaust and the 2 pipes don't meet up 100% so be ready for something like that to happen!

other than that you cannot go wrong with the price of the product! so if your looking for an inexpensive downpipe this might be the way to go.

Hope this helps a bit! Hope I don't start any arguements. I know if i posted this reply on the OTHER site it might spark an arguement. hehehe

Jon

 

The price is right on the HKS but as stated, don't go with it if you plan on serious mods down the road.

 

350 at the wheels is pretty wild in my book. I don't think that's possible without a turbo upgrade, in which case, you will have to look at the pricier bellmouth downpipes like (TurboXS, Godspeed, Scoobysport) or a twin dump design like the Perrin.

You can also look into the staged packages from Vishnu, TurboXS, and Godspeed. That will also enable you to see how much horsepower can be extracted from the mods.

www.Vishnu-Performance.com

www.turboxs.com

 

If you plan on staying with the stock turbo the HKS DP will work just fine. But if you plan on going to a big turbolike the PE1820 then get a bellmouth design DP.

 

I got the HKS and am very happy with it. I did get a cel light but fixed that with the help of Sub-Sonic. Its cheap and it does the job. But the Helix dp from www.gruppe-s.com looks promising.

 

ideally you'd want the wastegate exhaust to be separate and vent to atmosphere. for a car that is expected to pass smog, this is really not an option since all exhaust gasses must pass through a cat, thus in this case it'll be ideal for the wastegate exhaust to join back into the downpipe a little ways down so that it will not disrupt the exhaust flow from the turbo. but in the end, its really the design of the downpipe that will determine how well it flows, not its type.

350hp to the wheels is definetely a bit wild in my book. with some aggressive tuning and upgrades to the rest of the car that will support it, you MIGHT be able to achieve this with a vf-30, 34, or 35, though i'd say the turbo is definetely the limiting factor here. a larger turbo like the vf-22, greddy t518z, pe1818/20, etc., may be a better choice.

keep in mind that imprezer is making 300hp atw with a t67, greddy r-spl fmic, 18psi of boost, pump gas, tec-3, stock internals, and loads of other mods that will leave you drooling, though i'm pretty sure we'll be seeing higher numbers from him once he sorts out his new drivetrain and hopefully his uhh...displacement issues . also keep in mind that the 300hp figure is off of shiv's dynamics dyno on which a stock wrx averages at ~165hp.

oh and if you end up getting a japanese exhaust, that is, a catback designed for the jdm wrx, be sure to get a jdm downpipe as well. the lengths of usdm and jdm catbacks/downpipes are different.