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Old 05-18-2010, 12:16 AM   #1
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Question 2006 imprezza 2.5 performance parts?

i just purchased a imprezza 2.5 4cyl. fuel injected car today..lol im new to subaru..what parts would make the biggest impact on acceleration and or speed?
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Old 05-18-2010, 11:34 AM   #2
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Originally Posted by bondo007man View Post
i just purchased a imprezza 2.5 4cyl. fuel injected car today..lol im new to subaru..what parts would make the biggest impact on acceleration and or speed?
My suggestion would be to go tot he Naturally Aspirated (NA) (non-turbo) forum and read extensively.

Unfortunately, the 2.5L engines in the NA Subarus are not good candidates for big horsepower without significant (and expensive) engine internal modifications. They are poor candidates for turbocharging, and they are pretty tapped out for horsepower from the factory. The 2.5 liter NA engine si not simply a WRX engine without a turbocharger. They are very different. You can turbocharge it, but you can't run high boost and many people who turbocharge the NA cars blow their engine sooner or later.

The factory intake is actually pretty good already, but if you want an intake, go the the NA forum and search for the hybrid intake. Most aftermarket intakes make the NA cars run too lean without a tune. The hybrid is a DIY intake that flows more freely without flowing so much that it leans out the car. If you REALLY want an aftermarket intake, plan on an NA Accessport and a tune. Lots of money for not a lot of gain, IMO, but some folks do it and like it.

You will find lots of suggestions on the NA forum about exhaust. ~2.25-2.5 inch seems to be the magic numbers that you want to stay under for exhaust piping diameter. Big pipe/more flow is not always better here as these engines rely on some restriction to build low-end power. Go with big pipe and you will see some gains on the high end, but you'll lose some on the low end. If you want the Subaru rumble, you'll need to get unequal length (UEL) headers. You have equal length (EL) headers on your car from the factory because EL headers are better for power. Lots of people are willing to make the trade off in power and go the UEL route to get the Subaru rumble.

Power-wise, the NA Subarus are trickier to modify (and modify well), than other cars. A TON of research has been done already though, and it's all over in the NA forum. Research and reading will be your friend.

That said, the NA cars are no slouches when compared to other NA cars in their category. It just won't ever be a WRX.

The good news: Almost everything (if not everything) that will work for a WRX, suspension-wise, will work for your car. So when it comes to suspension and handling the sky is the limit.

I'll say it before someone else does (because this is NASIOC and folks can be pretty blunt) but if you bought your 2.5i thinking you could grow it into a WRX with mods, you can't. That doesn't mean that it's not a great car and that you can't do quite a bit to it that will make it even better, but many people on NASIOC will tell you that if you really want power, buy a WRX, or save for an engine swap...and they have a point.

Last edited by Ogden; 05-19-2010 at 09:40 AM.
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Old 05-18-2010, 10:55 PM   #3
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Ogden has it down, lol. Go for suspension and you won't be disappointed. I think I commented in your other thread on some things people were misleading you on.
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