I have a completely unmodified Subaru Sti 06...

Do you need to modify the exhaust? Does it mess up the car's compression ratio if you do, and then you need to retune the ecu?

I really happy with how the car goes, just doesn't have the idle rumble that the ones with the modified exhausts/turbo backs/catback do.

Modifying the exhaust seem to make the car lose trade value - correct me if I'm wrong - but just taking from my own experience when I went shopping, I looked for (and waited for) the one unmodified STi that was available!
I wouldn't even consider anything that had any kind of engine mods done to it.

Also it is an STi and goes super hard already so I'm probably answering my own question here, not worth changing the exhaust for all I know.

Only thing I might do to it is the EcuTEK retune which unleashes a few more BHPs and faster power delivery without affecting anything, anyone had this done on an unmodified STi? is it worth it?

Search button is your friend here mate.

There is plenty of good examples here of stock MY06 STI's with mild mods like an aftermarket catback system and a mild flash tune (verso or ecutek) getting some very nice gains in torque, hp and acceleration. This is well worth doing as it will improve the stock tune and drive by wire lag that comes with it, fuel economy can actually improve and your will get some subaru dak dak rumble.

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Funny looking German Subaru

Ever pass a thought about the people that semi seriously mod a car, then use it, then revert back to stock before trading? Eg Huggy b?

Everyone will have their own opinion.

Mine is that the car is probably fast enough as is.

You can add just a "diff back" exhaust (just a rear muffler) to give you the WRX exhaust sound, without needing to re-tune the ECU.

Having said that, a complete exhaust upgrade (turbo back exhaust) and ECU re-tune will net a nice handfull of power that will bring a BIG smile to your face, without the need to modify anything else (which keeps the car stock, and keeps the value!!!)

As above, depends on what you want, and how long you intend to keep the car. Be aware once you start, it can be hard to stop adding to your car.

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Race Torque Dyno 399 NM, 248Kw @ 20PSI

Straight roads are for fast cars, twisty roads are for fast drivers. I have or am neither.

http://tttmsp.smugmug.com/

Just get a cat back for the noise and keep the stock cat back for when you sell the car.

My STI is stock with a cat back and coilovers and it's plenty fast for me.

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hello my name is tommy
i don't have a Subaru

Totally Agree!

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MY06 STi

Fuck it.. mod the shit out of it.

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2016 Levorg GT-S
Old man spec.

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www.perth-wrx.com

Cheers for the advice...

Might just do the catback with an ecutek tune just to get the dak dak rumble and a bit more power via ecu.
Not sure about the turbo back as it's a more full on modification and really hard to go back to stock from what I understand from a Turbo back.

I'll keep the stock pipes for when I sell.

Now start saving