itll hurt the car if u have a check engine light, so make sure wen u get ur hks downpipe installed, u also get a reflashed ecu thats is programed to handle ur new mod.

 

yea
i bought it, and read about how it can be a problem i cancelled my order and got a helix down pipe to go with my helix up pipe

its worht the more $
i absolutely love the difference

 

since when does the CEL "hurt the car?"

there's no need to get a very expensive reflash to solve that problem when 2 bucks worth of parts from radio shack will do the trick. if you're not electronically inclined, a pony express MIL eliminator will do as well.

jm2c
ken

 

hehehe

the problem with the cel fix is
if you don't fix it, and you just have the CEL on all the time, you won't know if something else breaks your car :\

 

You could just pick up the CEL fix from www.gruppe-s.com No worries.

 

So what?! How many stock WRX's or STi's have problems related to the downpipe design? With this "bad design" and a cat, these are capable of about 400hp before its a restriction, and that is the cat, not the design.

Nothing wrong with the HKS or any other OEM style dp. The Bellmouth design isnt exactly ideal, though... you still get some turbulence. A divorced wastegate is probably the only logical upgrade from stock design. However, I have heard of cars "having trouble with boost" on a divorced wastegate cuz "it flows too well".

 

The stock downpipe flange sucks ***. It is a flow restrictor at stock power levels. ANY bellmouth downpipe is going to make more power, spool faster, and have a lower boost threshold. With the stock design, backpressure increases greatly once peak boost is reached. Imagine it like this-
You're at a movie theater, and there are 4 exit doors. Your movie ends, and all the people in the theater leave, but there are only enough people to need 2 doors. Now, 2 other movies end as you are exiting, and those other 2 doors are needed. Only, 3 feet past those 2 doors is a wall. How fast do you think the disgruntled moviegoers are now exiting the building? I don't know, but it's not as fast as it would be if that wall weren't there.

 

CEL doesnt hurt the car much but its not good to have cel on. air/fuel ration signals are messed up.

 

THEORY:


if you keep the wastgate closed longer, where is the air going? into your turbo, spooling it.

flat flange = more torque and/or quicker spool

divorced wastgates arent ideal, the wastegate opens on an angle anyway, so if its not fully open, the air is towards the larger pipe creating alot of turbulence anyway

 

Divorced downpipes usually come with a divider plate to keep wastegate gasses from going to the main exhaust flow. However, that is my theory with bellmouth downpipes, that the wastegate opens towards the exhaust stream and creates turbulence anyways.

 

You don't want your flange defeating your wastegate. It's there to control boost. By forcing it to continue 'spooling' the turbo as you put it, you are forcing more boost and/or overspeeding the wheels. Your wastegate does what it does for a reason. A bellmouth or divided wastegate helps it do what it does more efficiently. The flat flange most definitely does not affect spool, as I addressed in another thread. The wastegate remains closed until after the turbo has fully spooled and boost is reached. The wastegate exhaust and flange design only affect the efficiency of the exhaust at full boost. The less turbulence you create, the better the flow. The better the flow, the more power you make. Would you care to explain how the flange creates less exhaust turbulence than the other two designs in question?