So here's my situation:

I had to go back to stock cat back due to getting pulled over too many times (even though my decibel level is around 95 db). IIRC I lost about 15 hp/tq. I'd like to get that back if not more but keep it quiet when I need to.

I bought a used QTP downpipe with electronic cutout



, but it needs about $150+ worth of parts to get it working.

I thought about putting SoundPerformance.com's boost actuated exhaust cutout on it



or get a Map O2 Dump

.

It seems to me that both, the O2 dump and boost actuated exhaust cutout, would open up at about the same or close, depending on wastegate actuator settings, boost levels. Is this true or do I have it wrong? What are the pros and cons to these set ups. I know the pros and cons to the QTP with the electric cutout.

 

BTW, I have a viii turbo on the car now and a ix turbo with 19k miles on it on the work bench. Perrin DP, Perrin air intake, S2 cams, E85.

 

The sound performance website says it has an 11psi actuator or you could hook it up to a solenoid to open when you want. I'd hook it up to your 3-port if you are using ecu controlled boost. Done deal. Otherwise it would open the cutout before the dump unless for some strange reason you are running very low boost.

 

The dump seems more common and available used. The boost actuated cutout would have more control when I want to open it. Other than that I assume I can get what I'm looking for with either.

 

Our O2 dump only vents wastegate exhaust gases, those other two options would dump the exhaust gases that go past the turbine (which I believe is what you're concerned about in regards to the restriction from the stock exhaust). Let me know if that doesn't make sense lol.

 

I would do both. And get your power plus back.

 

That does make sense. So simply I didn't see it!

 

I think I just may.

Now the question is QTP electric cutout or SP boost actuated cutout. Personally, I'd like to not have to open and close the cutout. I think the boost actuated will open when I'm getting on the throttle (50% TPS+) and at a moments notice back off the throttle (<40%) and it's stock sounding again.

 

You can actually make the QTP cut out boost actuated by using a hobbs switch...

 

I learn something new everyday! Thanks, never knew about the hobbs switch! However, the QTP motor is so slow compared to SP actuator. I wonder what else I can use the hobbs switch for. It looks pretty cool.

 

If you get one from NAPA, pop the little rubber piece off in the middle of the two contacts, and you can actually set the switch to what ever boost pressure you desire... you could set the activation point lower that way it will be fully open when you are in full boost...

 

Thanks. I might have to try that. It may be the cheapest way to go with what I already have.

 

Please explain, I have an electric QTP dump but I'm willing to experiment with this to see if I'd like it better.

 

The hobbs switch is a pressure switch, so you set it to what ever boost you want it to actuate at... once it reaches that specific pressure the power is able to flow throught he switch and opens the cut out... pretty simple...

 

have maperformance make you a varex catback. im pretty sure they can make it for the 8/9 as they made one for me so they probably have a jig.

http://www.maperformance.com/map-sta...cbe-varex.html