Which engine is best, which would you choose personally ?
 

I'm caught between a rock and a stone at the min in deciding what is the best setup to get in a hatchback. Like everyone on here i love the flat 4 burble, my ears always wake up when i hear one coming in the distance.

I'd love to have the 2.5 engine but i know about all the issues which is a shame, ive heard the 2 litre twin scroll engine but it doesn't give me the same feeling as the 2.5 engine, it seems more smoother, less agressive sounding and really toned down as far as a scooby engine goes, it's as if it's not a scooby that i know if you get where i'm coming from. To get a 2.5 engine, have it close decked and forged along with 14mm head bolts and everything else needed to give you peace of mind is quite cost prohibitive, i appreciate the work that goes into them, luckily i have the money to do that but it's a long process, the build, the running in, the regular early oil changes and servicing initially plus you'll never see the money again.

The 2 litre twin scroll seems to be the sensible option but i know somewhere inside i don't want a sensible sound if you get me, i'm sure its a good engine, is it that much better than the 2.5 though, i appreciate it seems to be more reliable, it's all about fun owning a car and im not so sure it produces an aggressive enough sound from the engine for me, an Impreza is about stance, the iconic flat 4 boxer sound, aggressive looks and the fun to be driving one.

Any opinions on both engines would be appreciated, what direction would you choose in my position ?

Is the noise the primary concern, over performance or driveability?
I would say 2.0l twinscroll for B roads, 2.5l if you mostly hoon at over 70 mph, or run at high speed, more open tracks.
However, for me the deal breaker is the ability to get an immaculate import, with no under body corrosion, not some modded rusty old UK model with a £5k+ motor.
( or best of both worlds and get Rob Day's 2.5l twinscroll!!)
But it's not just the motor; imports give you options too....quick racks, spec c features etc. Call me biased, but I would have another spec c tomorrow.

And if you don't think a twinscroll sounds aggressive enough, go on Facebook, and look up Raggys page Jdm Hatch Ireland, and scroll through his videos to hear what an Invidia N1 decat sounds like!! It puts most sports bikes to shame.!!!

Thanks Hedge, i found one of his posts on here, that will give me some reading to do later.

jdm hatch ireland - Page 4 - ScoobyNet.com - Subaru Enthusiast Forum

But I would argue that there is no need to stick a bigger turbo on a twinscroll; there are a number of SN members who have gone the LM/RCM 450 route, and then regretted the loss of drive ability. "Plenty " has a thread on this for his new age twinscroll, which had originally been owned and modded by Shaun, no expense spared.

I have both the the ELH and UELH on my cars. I love the burble sound but that doesn't mean that the twin scroll screaming at 8k rpm doesn't sound awesome too. It's about the exhaust you run.

This is someone running the Tomei system. It sounds pretty good to me

My twinscroll blob with an H+S decat sounded incredible...no burble but an altogether more visceral and equally engaging noise. It has been described as being like a fighter jet.

On my hawk I tried a Milltek and an RCM exhaust but neither sounded nearly as good. The twinscroll sound is very exhaust dependent, more so than a single scroll.

That does sound good Adam.

No way thats getting near a track in this country :lol1:

My RA has a standard airbox and cat with the S202 titanium backbox and it is very subtle around town. Once you open the taps it comes alive though and sounds more refined and exotic than my other one.

It sounds great tho :lol1::lol1::lol1:

MY03 and newer 2.0 JDM cars potentially suffer the same ringland issues as the 2.5 simply because they use the same hyperpeutic casting process so its not a guarantee albeit they do offer greater security of heavier liners, etc......

the Subaru 'burble' is not related to the engine size / type in any way but is simply caused by the poor design of the original single scroll set-up due to the packaging issues
v.early Leggy Turbo's and early classic Impreza's have a far more unequal exhaust manifold than the later 2.5 etc and hence they sound slightly more "burbley".......

I'm at this exact point with my hatch, where I'm about to go 3" + sports cat. This means losing the beautiful but heavy STI back box.
My options are this Invidia titanium straight through single exit
https://cimg5.ibsrv.net/gimg/www.sco...3e8c47fe62.jpg
which will never get on a track.
And/or a custom fabricated twin exit , better silenced for the track, like this:
https://cimg5.ibsrv.net/gimg/www.sco...804647e62b.jpg
In my heart, I know I won't be able to live with the Invidia, should sell it on unfitted, but I can hear Mrs Boyle saying " Go on, Go on"
Having said this, the exhaust would NOT be the reason I would buy one car or the other.

On my forged 2.5 hatch I replaced the backbox and mid resonator with a centre silencer into quad tailpipes. Sounded well, and closer to the burble of a newage which I love.
https://cimg5.ibsrv.net/gimg/www.sco...e037288122.jpg

They both look very nice!
Do you plan on doing any track days?
I imagine that a loud exhaust in a spec c becomes very tiresome on anything longer than a 10 minute drive though, so that would sway me! :freak3:

my money is on a forged 2.5 not running too much power , parts are easy to get hold of plus in the bigger picture not that much cost wise , my last 2.5 was forged at 90k and ran with me for another 100k and was sold as a still running engine , cost wise you pay 5500£ or so for a full rebuild , it you own the car for 10 years then it’s worth the money , not too much power say 350 brake with a not too large a turbo , 350 bhp is within a sensible range of the reliability of the engine , i saw a cracked cs400 lining at 400bhp , small ish turbo so you don’t get loads of lag , my Fsti forged engine standard turbo is a vf41 , virtually no lag and goes like a stabbed rat it’s as quick as a modern golf r , mines a daily drive i do like the twin scroll but mpg is supposed to be not as good as a 2.5 , i can get 35mpg IF sensible 😂👍

if you choose stock engine, v7 ej207 and big port jdm sti heads,

built one, ej207 closed deck conversion with +2mm long rod and built big port heads,

and i wouldn't mind rumble if i were you

The thread sort of comes back to subarus failure , when they built the 2.5 why not stick to the trusted results of the 2 litre when building the 2.5 👍 they lost a lot of business plus buyers trust , on a separate note , my 2 litre sti jdm wagon with more power around 345 bhp , was destroyed off the lights and at higher speeds by my old fsti with around 300 ish bhp