mmmiddy

Looking to upgrade the exhaust on a MY01 WRX.

Should I decat the downpipe or the centre section?

I already have a STI back box fitted.

Not looking for huge power gains, or a lot of noise, just want to get a bit more of that flat four burble.

TSL recommend leaving the front cat for a bit more back pressure, but others recommend removing this and leaving the centre section!

All advice welcome.

Thanks in advance

warrenm2

i am amazed at people who say that back pressure is needed.... The only time it would be needed is if you have some kind of desire to burn more petrol and go slower.... (or maybe to mask some other problem..). If everything else is working correctly - you want as low as back pressure as possible

mmmiddy

You need some back pressure, that's how a turbo works. Low back pressure is just as bad as having lots of back pressure, you need to find a happy medium.

I take it you would remove the front cat?

warrenm2

no - you dont need back pressure - you need a pressure differential.... not the same thing

RRH

I would be inclined to work forwards from the back of the car- ie do the centres next. I think you can get a resonated centre from Magnex?

Try Jamie @ JW Racing, 0845 123 2829, he's usually pretty helpful.

If you can get a resonated centre then you could do the down pipe too without too much noise!

simon

preacha

It must be your birthday and Christmas rolled into one

Check out the general for sale page where I'm selling my TSL x2 mid pipes (more details there)

So... keep the sti back box, replace the resonator and 3rd cat sections = nice noise, more response & power

save a fortune mate as I'm looking only for £ 100