Unequal lenght headers on twin scroll

giantbigjohnson

giantbigjohnson

New member
Hows all, so probably something that has been discussed before, I did a search and didnt find anything so sorry if its a repetitive question. I bought another sti today (my 9th one) I went with the hawkeye 2.0 ej207 (bought from Rob on here) so some may know the car. I just love the the subaru rumble hence this being my 9th one,im more for sound than power, but as yous know the equal length headers make them nearly sound like an evo, I also know if I put unequal lenght headers on with the twinscroll it will sacrifice power and spool. The car is running about 400bhp anyway, so my questions are if anyone has been here before, can I just put the UELH on and suffer loss of power and not run the risk of damaging the engine, or will I need to map, or do I need to change to single scroll and map also? Thanks in advance. Steven
 
Welcome along
It just so happens I have a full UK turbo and all that goes with it setup aside ecu that you require
I can do a straight swop with you and save you the suffer off the twin scroll sound
Please reach out at my email address [email protected]
 
Well man ,

You’ll have to change the upipe and turbo aswell and possibly a few other parts along the way plus a remap for most likely less power and torque , more lag

Great user name btw
 
BazGF8 said:
Well man ,

You’ll have to change the upipe and turbo aswell and possibly a few other parts along the way plus a remap for most likely less power and torque , more lag

Great user name btw
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Thanks Baz, I still may consider doing it. Im all fornthe sound...😆 I had that user name from years ago, I know it says im new but im on here years have posts back as far as 2013.
 
you can do it, but will need a unequal manifold, uppipe, single scroll turbo and a map.

The purpose of a twin scroll is having essentially 2 separated routes from manifold to turbo so that it improves spool time and responsiveness, etc.
Fitting an unequal to a twin scroll (if you even find an single scroll uppipe that bolts to the twin scroll) would have more of a bad effect than the unequal vs equal on a single scroll turbo.
It inherently wont damage the car in any way (providing you can it mapped afterwards), other than hurting nearly every part of the performance from spool to top end tbh.

Spending min €1500+ (without changing anything that gets broken, old hoses, etc) just to get the scooby rumble is questionable for less power and, when the money could be spent else where first like maintenance or upgraded brakes, etc.
 
Your looking at a full system change like lads say headers, uppipe, turbo, downpipe,and remap and for slower spool . Most go the other way from single scroll to twin scroll for the faster pickup .
It can be done it’s just costs and parts
 
Appreciate all the helpful reply's, you only learn by asking and thats what these forums are great for, every day is a learning day, I did not know the UK hawk was a single scroll, I had watched videos of hawks and felt they sounded good but guess they were UK versions. the reason I bought the car I did is it was in my budget low mileage and very clean and wide track STI, if you know the car you know this. The answer is as I thought and to downgrade to single scroll, which I may still consider as I said I'm not all about bhp and some people spend 1500 on a full exhaust system to have a sound they like, but the 400 bhp is still nice and sounds fairly good when its pushing. maybe ill do something to make up for losing the rumble .(ill go start a thread about turbo surge and flutter :ROFLMAO:) i do like the sound of the wastegate flutter so im sure thats very achievable with the FMIC and induction kit already on the car. thanks again for the replys
 
At what point would it make sense to just sell the car and buy one with the sound you are after?
 
GORDON GT SERIES II said:
Have to agree with Mark both of us having a twin scroll, the power delivery, low down grunt and with a decat that banshee scream when the power really comes in just just awesome will soon make you forget what that Subaru burble ever was I know if did with me 😂
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sounds good, any sound clips of your one?
 
AndyC said:
Went twin scroll when I rebuilt mine. I was adamant I was going to do the full single scroll swap. But after putting 600km on the car now since I got it running the twin scroll will be staying. Yes the scooby burble is gone but the pickup and almost instant spool makes up for it.
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I think once people drive a twin scroll especially in anger they soon forget the burble, I love the sound when a twin scroll with a good exhaust comes on boost it's addictive
 
Do aftermarket manifolds add a little more burble.. I know equal length for twinsceoll and all, but the likes of a HKS manifold or something.. Would something like that make them a little more unequal and give a bit more burble while still doing what it has to do to make the twinscroll efficient... Just thinking out loud... Like are all aftermarket options exactly equal length... Or are some slightly more unequal than others with some staying true equal..
 
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