Custom exhaust question

[UndergroundR32]

I'm looking for some advice on a suggestion given to me by a friend. He has quite a bit of experience with high performance work, and has built his share of DSMs, so I take consideration in his advice.
Anyhow. I live in New York and lucky enough for me, am not required to pass emitions testing, being that we don't have any in my area. Because of this I'm making an exhaust, where I'll have an eliminator DP going straight down to a muffler, off of which will be a short section of pipe.
The suggestion made was that he make me a sort of Y pipe before the muffler, connecting a wire from a butterfly valve blocking off the secondary pipe on the Y pipe. When pulling up to the line, I could simply pull this wire which in turn would open the butterfly valve allowing the exhaust to pass freely into the atmosphere which would eliminate the backpressure caused by the muffler.
I was concered that depending on the valve used to block off the secondary exit into the atmosphere, at WOT when it was closed, it could possibly leak or open partly.
Would this be at all practical in your opinions?

 

[UndergroundR32]

Bump:
I'd appreciate at least so much as a yes that's practical, or no that won't provide more than 1 hp extra or so.

Anyone???

 

[STARION]

I think it would be more trouble than its worth. plus, depending on what muffler you are running, you may notice very little noise diffrence. I.E. Maybe you could just go with no muffler the whole time, it really isnt too loud. remember that our cars have a built in muffler.....a turbo.

If not, I would reccomend inserts. Basiclly, they are these discs that you spot weld directly into the end of the pipe, and they rob you of no horsepower, but do make it significantly quieter.

 

[kylemoto]

Your ldea should work.

Turbo cars are pretty sensitive to backpressure, and turbo driven cars have lots of it.

The idea isnt new. A cutout exhaust was a popular option back in the 60s. Yous will just be plenty loud!

Good luck

Kyle