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What should i expect to get by installing a HKS Down Pipe to my 2004 Subaru WRX?

I just bought a HKS Downpipe for my 2004 Subaru WRX. What can i expect to gain out of the installment? For Example: Will i get more horsepower? If i do get more horsepower, how much horsepower should i be expecting to get out of it? Will it sound louder?

Public Comments

1. absolutely nothing


2. You can expect to get a CEL...

   Unless you get it tuned that is. That's practically a stage 2 setup with cobb. If you go opensource tuning or protuned by your local tuner, you can expect more power. Can't say exactly you'll get, as each car is different, and respondes different with tuning, you [b]could[/b] range from 220awhp to 260awhp.

   As for louder, shouldn't be any much noticeably louder assuming you still have the stock catback.



3. about 15-20 hp with out a ecu tune. but you need to watch out for boost spikes.


4. Louder yes but not so much. Most of the loud will come from the cat back. So check which one you want. As there might we video of the cat back.

   Gain... Flow for the exhaust. This flow will allow your turbo to breath. This and a up pipe will be good. That is if you need an up pipe. Some years need it and others wont. As I can recall the 04 still has the cat in the up pipe. Removing that and doing the down pipe and adding a cat back. Will allow you to get a Cobb Access Port or get a open source tune for going stage 2. Increasing the turbo boost from 14.5 psi to 16.5 psi.



5. Without tuning and just installing the down pipe you can expect another 5 to 10 hp. You can also expect a blown engine from a terrible boost spike the first time you go full throttle. Get a tune to go with it and gain 35 to 45 hp and have great running car. just in case you missed it, do not install just the down pipe alone without tuning on an 04 and up WRX. Bad things can happen.


6. Like others have said, not much in the way of horsepower. There may be a slight gain, but it will FEEL less powerful than before you put the downpipe on. You will get a bunch of boost spiking, so WOT pulls will be out until you are tuned. Bottom line, the car will be slower. Also, the 04+ has a an open/closed loop fueling algorithm, which can be dangerous for your motor. If you do get a stage 2 tune on your car you can expect to be about 210-220 HP at the wheels. It should sound a little better, but you probably won't notice much in the way of a difference.