currently i run cat downpipe,straight through center pipe and a miltek rear silencer...the noise from the car is perfect for me,not too loud but a very audable rumble..... problem is i work shifts and often come home in the early hours of the morning and am about to replace the front pipe with a decat along with a turbo change,i dont really want the car to get any noisier as i actually like the neighbours...... i realise with the front decat on the noise will deff increase...i have the original jap spec resonator center pipe lying around and wondered how restrictive this is compared to the straight through pipe? its just a baffled tube from looking inside it,i know it does make a difference to the sound as i ran the miltek on its own first,and then fitted the center and it deff got louder..... if its only a few brake horse power difference then that will be fine as im not chasing max numbers here,if its going to really strangle the car im not so sure.....

martin

 

not really that restrictive at all as far as im aware, mine happily had well over 350 running through it

 

go for the de-cat dp mate, - sound quality will degrade but I think the drive-by noise level is dominated by your back-box anyway so the neighbours should'nt notice any significant difference. Where the de-cat really matters is in terms of driveability, - the turbo will spool up to full boost almost 1000rpm earlier (based on my 97MY Classic) and the low-mid speed torque curve will be a lot less lumpy.

 

Worth trying as it will drop the noise down and the only "restriction" would be a tiny bit of turbulance caused by the perforations. You would also benefit from less drone on the motorway.
JohnD

 

exactly as JohnD says, the straight through pipe was way too loud for me, the resonator brought it right back down to sensible levels without loosing any power

 

My car running circa 400BHP with a resonated centre, and i know of a 485BHP WR1 doing the same. its not a restriction in the same way as a cat, more like a straight through baffled tube.

 

I had a full decat and the noise was offensive I fitted a resonated decat prodrive centre pipe and the noise is more than pleasent now and it is mapped to about 340ps so not to bad.

 

Harveys headers and uppipe, 3inch open neck down pipe, resonator and fujitsubo from there and I'm at 93db at 4500 rpm FWIW.

 

Thanks guys......exactly what i was looking for,ill refit the resonator when i decat the front pipe.......

 

Hi,

As an "oldie", my solution to this problem was, believe it or not----refit the standard backbox twin-pipe pea-shooter!
Car is a MY99 lightly modded Turbo wagon running full de-cat and Ecutek, making 260bhp last time on rollers.
Just a thought as most agree that replacing standard backbox only gains a few bhp but standard backbox is of course much quieter than aftermarket items.
Dave.

 

Dave... its a thought,and i agree the pea shooter box will probably solve the noise problem,but i think i may well try the standard jap spec resonator center pipe first,as i think that may well be enough of a muffler to the sound,as stated the actual sound is more or less dictated by the rear box,the actual sound itself is at the moment excellent,as in tone,its just the possible level increase with the decat pipe added

agreed standard back box replacment alone will only yeild a couple of horsepower.... if any... but thats with the standard restrictments (cats ) still in place... with these removed i would think the standard rear silencer would be very restrictive on the improved gas flow of the decatted system

plus the peashooter is butt ugly and was the first thng removed for that reason alone.... lol... have still got it though


im not actually classed as a youngster myself anymore,as ive passed the midlife point....noise i generally like,and can get plently of aural enjoyment on my buell with race pipe..... but i dont ride that home at between 3-6 in the mornings when i get off shift.... this is hopefully going to allow me to maximise the mods im intending to carry out....but still stay on the good side of the locals

 

if i could make the pipe 3.5" bore in to the twin peashooters id do it

 

Just to add, so as not to mis-guide, the Fujitsubo TI is a particularly civilised back box.