pimpalicous

okay i have a 1994 wrx wagon import
i have seen three types of de-cat

1.flat face- only has a hole for the gas to escape from the turbo not the wastegate heard these are the worest of the lot so not even considering these am i right?

2. open mouth/neck-heard these are good and are the most commonly used

3. twin pipe-a pipe with one big bore pipe from rear of turbo and another smaller one coming from the wasegate part then both coming together just after halfway down the pipe.

now here is where im not sure what to go with i can see how the twin pipe theory works by taking away the swirling and vortec created by the two gasses mixing causing less back pressure from behind the turbo making it more free flowing but the open neck is about 20 quid odd cheaper is it gonna be much more superior than the open neck or...?? or have i got it all wrong and the open neck is better or the fllat face?? help...

pimpalicous

anybody???????????

[Davey]

The waste gate and turbo outlet are the same chamber so the open mouth pipes make the most sense.

silent running

1. Never heard of that sort.
2. Yes I suppose they could cause wastegate/exhaust flow turbulence but then again unlike some turbos, the Subaru design has both the wastegate and turbine exits facing the same way.
3. Twin dump arrangements are useful for where you have turbine and wastegate outlet at right angles to each other. This is not the case on a Subaru's turbo so it seems to be just a pointless over-engineering of the downpipe which will simply restrict flow from both outlets.
4. Option 4 is one of my own...with the new MOT regs i.e. computerisation and data logging involved with every car going through the test, there will no longer be any bent tickets doing the rounds, or friendly MOT testers who will fiddle the emissions. It's totally pointless for the hassle that it will cause them. Gone are the days when you could run around all year with a decat pipe on and then your tester would wangle it for you at MOT time by putting down slightly different figures or waiting for the car to reach full running temp before checking it. Unless you are happy to physically take your decat pipe off just before your MOT, change it for your cat pipe, then put your decat back on, every year, then just accept the way things are now and get a SPORTS CAT pipe.

pimpalicous

cant say i agree with option 4 as im after power not convience.

i have ended up buying the twin pipe desighn after lots of looking and talking to people it seems this is the better choice thanks for all ya help

scoobfan

I also have a WRX Wagon and have just bought the open neck pipe on
the Hayward & Scott group buy.

It's 3" reducing to 2.5", I'm led to believe the open neck is the best option
and most commonly used on the high powered cars.

I'm also going to heat wrap mine for better gas flow, but mainly to lower
under bonnet temps.

Rob

pimpalicous

yeah im also heat wrapping mine heard its a very good thing to do only costs abit so is worth doing if only to get a small gain. will let u know how i find the twin outlet to be

axgt_bwaii

iTrader: (6)

i have a 93 wrx fully decated and it pases mots legaly passed one in january.

its not runing lean. its something to do with being an early import and that uk emissions testers dont have the cars year details on the computer.

stew