(01-07-2016, 08:07 AM)barrote and why u want to mess with that, may i ask?

(01-07-2016, 08:34 AM)barrote i see...

(01-07-2016, 12:18 PM)DiseaselWeasel Many modern "performance" cars have those (inside the mufflers). That's where the fart noises come from on modern cars

Though many on here fit "straight pipes" without receiving negative feedback... This makes it switchable. So? I've once tried a pipe instead of the oxidation catalyst (which I need for tax reasons) - the result was a notably faster spool (stock engine, stock turbo, stock mufflers). Not more power, but "better" power, if that makes sense. And you could hear the turbine whistling after this mod. So, I can imagine that cutting off the silencer(s) might yield even better results. On the other hand - the difference was all but spectacular...........

But would I fit a valve in there? I can't imagine this working well (heat expansion, soot) for a prolonged time... And then there's that noise thing. It's just not polite. Yeah yeah, race trac, private roads only etc. - we all know what that means ;-)

(01-07-2016, 01:51 PM)m1tch

(01-07-2016, 12:18 PM)DiseaselWeasel Many modern "performance" cars have those (inside the mufflers). That's where the fart noises come from on modern cars

Though many on here fit "straight pipes" without receiving negative feedback... This makes it switchable. So? I've once tried a pipe instead of the oxidation catalyst (which I need for tax reasons) - the result was a notably faster spool (stock engine, stock turbo, stock mufflers). Not more power, but "better" power, if that makes sense. And you could hear the turbine whistling after this mod. So, I can imagine that cutting off the silencer(s) might yield even better results. On the other hand - the difference was all but spectacular...........

But would I fit a valve in there? I can't imagine this working well (heat expansion, soot) for a prolonged time... And then there's that noise thing. It's just not polite. Yeah yeah, race trac, private roads only etc. - we all know what that means ;-)

I am running my W210 debackboxed which does make a difference with the spool, on the road I need to have the cat fitted, however on the track I obviously want to have little restriction to give a faster spool. The issue I have is that I need to drive to the track in the car so I thought about installing one of these in the downpipe - this will mean that for every day driving I will be running the car through the stock system and have the cat for MOT reasons. Then when I get to the track I can then open the valve so that its simply a pipe going from the back of the turbo down which will give me the extra exhaust flow I would want for a quicker spool.

Even with a straight through system there will still be restriction considering its got quite a bit of pipework to go through, plus I would still need to have the cat in place. If I install a cutout valve in the downpipe this will allow me to bypass the cat when I need to for off road events, then close it up when I drive home.