Quiet 3" backbox for classic Impreza, Revolution?

Andy916 · Post by **Andy916** » Thu Feb 26, 2009 4:05 pm

Anyone around these parts have a Revolution or similarly quiet 3" backbox on a classic Impreza? Interested to have a listen against my HKS Hiper 'Silent' system, which I'm finding intrusively loud on my RA. Mind you, everything's f.loud on the RA! Also interested to swap the HKS for something quieter, especially before the car gets mapped in a fortnight's time.

Andy

Gerry H · Post by **Gerry H** » Thu Feb 26, 2009 5:03 pm

The Revolution system is flanged at the downpipe but from then on is a push together system with clamps so you'll need the lot.

Have you a dB reading for the HKS?

Quiet and free flowing don't sit well together.

blacky · Post by **blacky** » Thu Feb 26, 2009 5:31 pm

+ if the Revolution system is anything like the downpipe I had the quality isn't all that impressive...

I bet your HKS isn't that loud really, its just the car has no sound deadening. My Evo is quieter on a run than the Impreza with a HKS Hyper or whatever but on tick over the evo is louder than the Impreza!!!

PS it'll be louder once its mapped as well on boost!

duncan · Post by **duncan** » Thu Feb 26, 2009 6:45 pm

Gerry H wrote:Quiet and free flowing don't sit well together.

mine seems to cope alright and with centre resonator too. 93 DB at 5300 rpm and i think you have an idea of the power figures

Miltek 3 inch decat.

Gerry H · Post by **Gerry H** » Thu Feb 26, 2009 7:19 pm

duncan wrote:
Gerry H wrote:Quiet and free flowing don't sit well together.
mine seems to cope alright and with centre resonator too. 93 DB at 5300 rpm and i think you have an idea of the power figures

Miltek 3 inch decat.

Mine's been noise tested to 93 or even less on occasion. When you eventually get yours out on track, you'll be interested, or horrified, to learn that the drive by figures can be considerably more. My '93dB' Evolution wasn't quiet enough to save me being kicked off Donny.

Fast Eddy · Post by **Fast Eddy** » Thu Feb 26, 2009 7:59 pm

Andy,
What tailpipe does it run. I find that this affects exhaust sound. If is like 5" single wall it will cause resonance in the tailpipe.This also affects flow. Rally cars do not have flashy tailpipes, they keep the same bore all the way through which maintains exhaust velocity.
I have 3" stainless boxes in stock with Subaru style tailpipes that are not overly loud as they have a special silencing system that does noy affect flow noticably.
Give me a call to discuss mate.
Eddy

Andy916 · Post by **Andy916** » Thu Feb 26, 2009 9:50 pm

Hi Eddy,
I think it is 5", yes, and single-wall. Feckin huge. With bung in it's not that bad tbh, and not that loud outside the car. At 90 it's gone entirely but road noise is loud - very much louder than an ordinary STi classic. As Logan says, it's the car mostly, I think.
Andy

duncan · Post by **duncan** » Thu Feb 26, 2009 10:31 pm

Gerry H wrote:Mine's been noise tested to 93 or even less on occasion. When you eventually get yours out on track, you'll be interested, or horrified, to learn that the drive by figures can be considerably more. My '93dB' Evolution wasn't quiet enough to save me being kicked off Donny.

Not a hope of any drive by pass on a quiet day at Donny or Bedford. Noisey days are fine though.

Mine has been on track plenty of times thanks Gerry

ScoobieWRX · Post by **ScoobieWRX** » Thu Feb 26, 2009 10:49 pm

Why not get one of those slot in baffles. They go into the end of the tailpipe like a bung. Couple of grub screws keep them from blowing out and there are others that have a lip that slots over the tailpipe and held on with a clamp.

Instant silencer for your trackday then take them of afterwards.

Gerry H · Post by **Gerry H** » Thu Feb 26, 2009 11:59 pm

duncan wrote:

Mine has been on track plenty of times thanks Gerry

I meant in it's latest guise!