I am currently running a pretty much standard 2004wrx but it has a Subaru WRsport backbox on it.

At Cadwell park last year it easily passed its noise test with a db reading in the low 80's.

Im after a bit more engine burble but need to make sure I can still pass trackday noise levels. Just bought an unsilenced centre section and wondered if anyone has a similar setup/knows what sort of db reading I should expect?

 

Don't think it will make a huge difference to be honest - do you still have a downpipe cat?

If you really want more burble, a different backbox is probably required, it will be louder though.

 

Its an easy way to get more burble and some pops as well did it last week to my 03sti ppp and I highly recommend it.
£90 ish from haywood and scott.

dipster

 

BTW I dont think the std center section has a silencer, its a resonator used to remove some of the burble.

dipster

 

Ok, thanks for the input guys.

Still got all the cats in right now. I know removal gives good bhp increases but I don't really need anymore power just yet as want to get the handling sorted first. Working my way from the back in stainless!

So if its just a resonator to suppress the burble then a straight though pipe should give more 'burble' than 'noise', so should still be ok for trackdays? I have bought a 2nd hand afterburner centre (made by h+s I believe) which should be arriving today.

Is there anywhere that can test my db reading? Do you think they would test it for me up Cadwell if I popped up there before my trackday?

 

Im in the same boat mate. I have a PPP Sports cat down pipe, H&S 4.5" Backbox and now looking for a centre section. Its already fairly loud, so I would also like to know would a non-resonated centre section make it much louder? My 04 STI has a centre cat as well, is that on a different pipe to the one in question?

 

It will be a little louder and will sound deeper anyway.

dipster

 

The 2nd cat on the 04sti is in the pipe before the center section.

 

This is the bit I have bought:



Impreza Turbo 2001-2005 New Age : Subaru Impreza Afterburner Stainless Steel Centre Section

 

When I spoke to Ian @ H&S a full decat 2.5" system with a classic design BB on a newage STI was 96 decibels as they tested. This is what I have on mine and yes its burbely and yes it pops/bangs/flames but under 100dB will still allow it onto pretty much most tracks.

Obv I am going to get it tested prior to any track time

 

Oh and removing the resonated centre section and the 3rd cat on the mid pipe will free up a lot of the noise you are after while still allowing it to pass an MOT. Had this set up on my old Bugeye WRX.

 

Arrived, Fitted, Well happy!

Has a deeper noise on tickover, then comes alive with a rasping subaru burble at 3.5k revs!

Looks alot nicer than my rusty old original and being stainless it should last alot longer too.

Get youself one of these!