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Old 02-08-2011, 11:59 AM   #1
sdelorge
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Default Bang for your buck performance boost for 08 impreza

I am looking to increase the power on an 08 hatchback non turbo impreza.

However, I would really love it if I could increase my MPG as well.

What is the best way to go about this. It seems difficult for the non WRX or STI to find parts
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Old 02-08-2011, 12:19 PM   #2
Ogden
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Search and read, read, read, my man. There are a million threads on this very subject. (Okay, not millions, but tens certainly, maybe even hundreds)

In short, and before you get your first "swap it or trade it" response, the car is largely tapped out for power right from the factory. This has been discussed and there is a ton of information on it available.

If you want the details, you can find them in this forum and the Impreza forum in previous threads. If you want the concise and short version, it's not what you are wanting to hear but: Your money is much better spent on suspension than HP. You can go for HP, but you'll spend a TON of money for not much more power.

You'll find information about MPG as well, but there is only so much you can do with an AWD car.

Last edited by Ogden; 02-08-2011 at 05:21 PM.
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Old 02-08-2011, 03:58 PM   #3
royalnewjersey
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^^^ What Ogden said.

Just to add to that (while still being helpful), definitely look into suspension, tires, sway-bars, and handling mods before looking into HP. These mods will make your car drive like a million bucks, and definitely be worth your money. Throwing money at horsepower mods will only leave you disappointed, feeling like you're spending hundreds to get a few ponies out of the engine.

Try picking a direction for the car first, and work on your modifications based on how you want the car to drive. Don't just jump in and buy something because someone else has it on their car. Also, our cars can look really clean compared to a lot of others on the road. Lower it, tint it, polish it, do whatever you think makes the car look good.

And as a note for parts, many people will tell you that the naturally aspirated impreza crowd are stingy, picky, and whiny. Many part manufacturers stray clear of N/A mods, or end up discontinuing them because they don't make money. Some companies can support their n/a lines because they also make a lot more from their turbo car modifications. Check out rallitek, perrin, whiteline, cobb, turn in concepts, and AVO. These companies are a great place to start with N/A mods.
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Old 02-09-2011, 12:07 AM   #4
littlec
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vote for sticky. well said to the above two.
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Old 02-09-2011, 10:46 AM   #5
sdelorge
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thanks I am going to read into some threads I just didn't have time right away.

I figured the possibly of increasing HP wasn't that good especially for a good price. I'm sure there are a few things that can be done to get some serious increases but they will be expensive and/or reduce mpg

I guess what I am saying is that power isn't a must I mean if it was really important I would get a WRX. I am more interested in a 2-4 MPG boost. If possible. I know the impreza won't be getting in the 30's but 25 or 26 combined would be nice. I know it takes a hit from the excess weight from the awd but hey thats half the reason why i love the car. I know I could always look into weight savings but that doesn't seem to do a ton.
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Old 02-09-2011, 12:23 PM   #6
je255j
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I have an '09 Outback Sport, and I also don't have terribly large appetite for power. This car gets me by most days of the week just fine as is, but like you, I was still looking for just a little bit of extra power anyway. Living in Colorado, my problem had been that when I head West to ski/snowboard, the car really struggles in the mountains. Again, fine around town, but downright anemic up there.

So, what I did, and I'm recommending it to you because I feel that it really did have positive results for me, was to replace the air filter with one by K&N, and replace the exhaust and muffler with the stock exhaust and muffler from a WRX. That pipe is just a little bit wider, and the bends are all exactly the same, so it's a very easy swap.

Now, the amount of air I'm able to pull in, and push back out, might only be a little bit more than it was, but it has meant the difference between the car maxing out at 75mph instead of 70mph. That's right: full power, pedal mashed into the carpet, "manumatic" shifter thrown until it's beeping at me because I can't downshift any more, and this car can only pull 75mph up some of these hills. The air is thin, and the roads are steep; if you don't live here, you might not understand, but the point is, 75mph is still faster than 70mph, and I credit that entirely to this mod.

Around town, I haven't noticed much/any change, but remember, around town, I also don't drive at full throttle, so I hadn't been looking for change anyway.

This mod may or may not help you. I don't know what your needs are. But, based on what I wanted, it definitely worked. And, considering I bought the stock WRX exhaust from a guy on Craigslist who had just upgraded his own, it was relatively cheap too. If you happen to stumble upon the parts, I recommend trying it.

Last edited by je255j; 02-09-2011 at 12:51 PM.
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Old 02-09-2011, 12:28 PM   #7
je255j
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Of course, that all said, even more power would still be nice. I have to admit, I do sometimes find myself wishing I had bought a WRX, or at the very least, a 2.5 Premium. Then I try to remind myself that those people (I'm jealous of) need to feed their turbo-charged motors premium gasoline, while us N/A people can get by just fine on regular. So, ya know, that kinda helps. A little.

Last edited by je255j; 02-09-2011 at 12:41 PM.
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Old 02-09-2011, 12:56 PM   #8
Lord Grippington
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When I added a stock '07 WRX rear swaybar(17mm vs. 13mm), that I got for free, it was far and away the most noticable of ANY mod I'd done or have done since. Real power gains are expensive with the NA motor.
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Old 02-09-2011, 02:37 PM   #9
dmasta46
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^^This!!

I just installed the rallitek 19mm rear sway bar for my 2.5i, and it made the world of difference. I now understand the meaning of the word "tuck"
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Old 02-09-2011, 06:02 PM   #10
keylay
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Quote:
Originally Posted by je255j View Post
I have an '09 Outback Sport, and I also don't have terribly large appetite for power. This car gets me by most days of the week just fine as is, but like you, I was still looking for just a little bit of extra power anyway. Living in Colorado, my problem had been that when I head West to ski/snowboard, the car really struggles in the mountains. Again, fine around town, but downright anemic up there.

So, what I did, and I'm recommending it to you because I feel that it really did have positive results for me, was to replace the air filter with one by K&N, and replace the exhaust and muffler with the stock exhaust and muffler from a WRX. That pipe is just a little bit wider, and the bends are all exactly the same, so it's a very easy swap.

Now, the amount of air I'm able to pull in, and push back out, might only be a little bit more than it was, but it has meant the difference between the car maxing out at 75mph instead of 70mph. That's right: full power, pedal mashed into the carpet, "manumatic" shifter thrown until it's beeping at me because I can't downshift any more, and this car can only pull 75mph up some of these hills. The air is thin, and the roads are steep; if you don't live here, you might not understand, but the point is, 75mph is still faster than 70mph, and I credit that entirely to this mod.

Around town, I haven't noticed much/any change, but remember, around town, I also don't drive at full throttle, so I hadn't been looking for change anyway.

This mod may or may not help you. I don't know what your needs are. But, based on what I wanted, it definitely worked. And, considering I bought the stock WRX exhaust from a guy on Craigslist who had just upgraded his own, it was relatively cheap too. If you happen to stumble upon the parts, I recommend trying it.
How does that WRX exhasut sound on your OBS? Do you have any drone or annoying Honda type sound? I also have a OBS with a automatic and i'm worried that if i get a exhasut system, it will be unbarable when driving as I can't manipulate what rpm it runs at. Is it much louder inside?
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Old 02-09-2011, 06:22 PM   #11
Ogden
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It's not loud at all. I also have the WRX OEM cat-back on my Outback Sport. It adds a little bit of extra sound to the car but it's not what you want if you are trying to get more "sound".

I did it because I read that the 2.5 inch exhaust was optimal for the 2.5L NA engine and I found someone local selling one used for $70. Otherwise I'm not sure that I would have bothered with the exhaust at all.
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Old 02-09-2011, 08:43 PM   #12
keylay
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Quote:
Originally Posted by Ogden View Post
It's not loud at all. I also have the WRX OEM cat-back on my Outback Sport. It adds a little bit of extra sound to the car but it's not what you want if you are trying to get more "sound".

I did it because I read that the 2.5 inch exhaust was optimal for the 2.5L NA engine and I found someone local selling one used for $70. Otherwise I'm not sure that I would have bothered with the exhaust at all.
Just what i needed to know. When i was younger, i installed a straight through 'bullet' style muffler and duel tips on a 4.0 Ford Explorer and it was obnoxious....oh gosh i hated it. I don't want sound at all, but for $70, it's hard to beat any performance gains there may or may not be. I'm guessing it's just a cat-back that's the same since we don't have down pipes?
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Old 02-10-2011, 12:16 PM   #13
je255j
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I concur. The sound is almost negligibly different. If I were to rev my motor next to a stock OBS, mine is probably a bit louder, but, A) not in an obnoxious way, just in a simply "less quiet" way, and B) so slightly that I doubt you'd even notice without the side-by-side comparison. I know the sound you're afraid of, and this definitely isn't it.

I paid a little more than Ogden. The seller I found wanted $90. I think it's a worthwhile investment at either cost.

Oh, and yeah, it's just the cat-back. We have no use for the WRX's downpipes.

Last edited by je255j; 02-10-2011 at 12:21 PM.
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