angry1

Yes im stupid what is a deresonated is it a straight through pipe that removes the center CAT
i have wrx 04 and what better sound so i have just bought a prodrive back box.....some one adviced a deresonated centre section and where will i get one for how much thanks all in advance

53

iTrader: (41)

A straight through centre pipe removes the centre resonator, the rear centre cat comes after the downpipe before the centre pipe. Your not stupid mate which is why you asked the question Price for a de-res centre is about £100.

B0DSKI

iTrader: (17)

And makes a whole lot of difference to sound and throttle response IMO

The rookie

iTrader: (1)

Strictly the centre section doesn't have a resonator, its a silencer (its only Classic STi's that have a true resonator), I don't believe that changing that will have one iota of an effect on throttle responce that far from the engine, but it certainly 'improves' the noise.

Simon

Flaps

iTrader: (1)

I've an 04 WRX too and have been considering one of these but with the standard backbox. Scoobyclinic do them for £85 fitted.

53

iTrader: (41)

It does rev more freely without the resonator/silencer, throttle response from a smoothness point of view rather than power

Shark Man

If we're talking centre cat replacement pipes; there two options one straight through, other with a small straight-through type silencer box.

Unless its a crap quality exhaust...The latter has the same internal bore through the silencer as the straight through pipe so no difference in restriction, just noise.

Removing the centre cat is what makes the difference in restriction.

53

iTrader: (41)

On a new age car like angry1's car, you have the resonated centre pipe and then a rear catted centre.

The centre pipe has a resonator/siliencer the rear cat centre has a cat.

The centre pipe can be replaced for a straight thought pipe which does not have a resonator/silencer, this gets you noise and smoothness

Stainless exhausts manifolds headers

The rear catted centre can be replaced for a de-catted rear centre which does not have a cat, and you get 'some' extra power

Stainless exhausts manifolds headers

teaforvicar

It is also worth noting that if the car is a newage WRX with Prodrive Performance pack fitted then this includes the removing of the Cat in the centre pipe anyway..I think this is correct..

53

iTrader: (41)

You are correct

You can also get a decatted down pipe or sports cat down pipe made as one piece to include the rear centre if you are remapping for more horses. And while you're there, you may aswell get a decatted up-pipe for good measure

Shark Man

....and a remap....and a.....

The rookie

iTrader: (1)

The only part of the exhaust post cat that the STi PPP doesn't replace is the centre section with the small SILENCER (as above its NOT a resonator in the proper sense of the word).

Simon

teaforvicar

So, if like me you have a WRX Newage with PPP getting an H&S centre section would only increase the noise not give me any extra HP... I assume?

The rookie

iTrader: (1)

On an otherwise stock PPP, no, only if your going full 3" system with decat (illegally of course) and pushing the TD04L to the max will you get any (small) benefit.

Simon

53

iTrader: (41)

Assuming you mean the centre pipe with the SILENCER and not the rear centre with the cat then that is correct, but there are other drivability benefits of replacing the silenced centre section with a straight through pipe