Thread: Boost activated cutouts

I've always been interested in these cutouts. Especially if you have an electronic boost controller where you can set high boost to open the cutout. Years ago ATP used to sell this, but it has been on eternal backorder:



Another option is the Sound Performance one, but it comes with a hefty price tag at $400:



And I just found this one today, obviously a Chinese piece, but a lot more affordable at just over $100 shipped:


This last one is being sold by two companies, Epman and Autofab:
Aliexpress.com : Buy NEW Boost Activated Exhaust Cutout / Dump 63MM Open Style Pressure: about 1 BAR TK CUT63OP BOOST from Reliable exhaust nissan suppliers on EPMAN RACING SHOP | Alibaba Group
Wholesale AUTOFAB - NEW Boost Activated Exhaust Cutout / Dump 76MM CLOSED Style Pressure: about 1 BAR AF-CUT76CL-BOOST - Alibaba.com

Anyone have any experience with the Chinese one? How about making your own out of an Electronic cut out?

Why not just get another wastegate, but larger?

Many BMWs and other cars have these built into their exhausts now. You might be able to source something from these cars or the parts counter easily/cheaply?

Reason for wanting this, is to keep a quiet 2.5" exhaust, but at higher boost let it dump out from the downpipe for more power. My setup is a simple DET with the stock turbo.


I've seen that, not sure if a BMW part will necessarily be cheaper than the Chinese one.

We're talking about the same thing.... if you notice those products are using an internal WG actuator to open a valve.

Just put another (larger) external WG directly on the exhaust (with a smaller psi spring than the WG controlling the turbo)

That would work, but it wouldn't open as much as the one pictured, and would also be rather spendy to get, say, a 60mm WG. That being said, I doubt the one pictured would seal very well as thats usually the main issue with cutouts. They always leak

I'd need a pretty large external wastegate to match up to a 3" exhaust cutout.

I know some leak, that was my biggest complaint with the quicktime one I had about 10 years ago. Some of the electric ones I've seen now look like they seal a lot better.

I think an eletric unit would server you better. It sounds like you are running a NEMU or standalone ECU. If so...

You could configure your ECU to open when you have high boost active and are over 80% throttle or something like that and it would aid in your spool time.

If you are dead set on it going off at a boost psi then you could have it activate when the MAP sees X.XX voltage. This will work even if you use a MAF as your load source.

This car is pretty old school, still on a JWT computer.