In pursuit of a little more noise, my next modification was the fitment of a non-resonated centre pipe.
In stock form, the standard Subaru centre pipe has a resonator right in the middle of the pipe. You can see it in the image up top. That’s no good for anybody if you’re looking to unleash the natural burble of your boxer engine.
To improve the sound and get the pipes a little more free-flowing, fitting a non-resonated centre section is the way to go. Scouring the classifieds, I managed to find an ultra bargain of a centre pipe, pre-owned.
So in anticipation of fitment, I set about procuring the required hardware. On one end, the centre pipe attaches to your backbox/muffler with a couple of standard bolts and simple thin gasket. I’d already recently purchased the hardware for this end when re-fitting my repaired Prodrive exhaust.
However at the other end it’s not quite as simple as you’ll be attaching it to the cat/midpipe. You’ll need to find yourself a special fitting kit which comprises of a couple of spring-tensioned bolts, and a ‘donut’ o-ring/cone ring gasket.
Something like this, or this, or this – take your pick.
So then on to fitting the centre section – and here’s where I had a little trouble. Unfortunately the second-hand centre section I had bought previously was just marginally too long to fit on my car – apparently it had come off a 2003 STI, as mine is, but I have my doubts. Here are a couple of comparison shots – you can see it’s just a little longer:
Perhaps it was originally from a Forrester or Legacy or something? I have no idea. But it promptly got sold back on, and I set about purchasing a BRAND NEW centre pipe this time.
Brands don’t really matter for such a simple part – it’s essentially an angled pipe – but I opted for a lovely looking pipe from Scorpion Exhausts. Made here in the UK, and with a full warranty, I know it’s going to be a well made part (that will actually fit this time!) I believe it cost in the region of £90 delivered.
P.S. Somebody please correct me if I’m wrong but I’ve also heard that Scorpion were actually the fabricators of the original Prodrive PPP backboxes back in the day…
Here’s a comparison between the new pipe and the original resonated centre section:
So how does it compare? You’ll probably read a dozen different opinions as to whether fitting a non-resonated centre section is worth it. Personally though, 100% worth doing. I can definitely hear and even FEEL the rumbles more now. You may find others say that removing resonators increases exhaust drone, but not in my case.
Obviously every car is different, driving styles are different and environments are different. So for such a cheap modification, I’d recommend giving it a go and forming your own opinion.
I’m very impressed!
Note: this was originally fitted in 2014, and as of writing is still going strong. Definitely worthwhile.
