Just a quick background information. My previous car was an heavily modded Audi TT, so I'm very familiar with the Bosch diverter valve (several version of it also) -dynoed at 250 rwhp and 270 rwtq on an AWD dyno (91 oct), and I had a custom race program which uses 100+ oct running (not dynoed, but considerably more power), running 27 psi on a stock K04-023. I had been modifying for about 4 yrs, and experimented with different dvs and bovs.

This isn

 

Given that you have some experience in this area. What would be a better aftermarket replacement for the Bosch diverter?

 

I've tried several types of dvs - both piston and diaphram versions. Forge Motorsports out of the UK has a good reputation with the VW, Audi, Porsche people. They have several types that would be a direct replacement for the Bosch.

007P, Piston type



or

007PA, piston with angled top



You can change out the springs to different spring rates, as well as service (relubing) the innards. The dimensions of these are so that you can pretty much take out the stock dv, and replace it with one of these.

Here's the instructions for servicing the dv, as well as doing a leak test:

DV Servicing

These are the diaphram version (DVR)



This is an adjustable DVR

DVR-A



The diaphram version responds more quickly than the piston type. Like I said, these are direct replacement. Both the inlet/outlets are 1" (25mm). Although, the daiphram doesn't hold as much boost. Given most sc only put out 6-9 psi, and 14 tops, the diaphram would be the way to go. On my TT, I used the piston type because it held boost better. However, with my SC, I would go with the DVR. Quicker response, and doesn't need to hold as much boost.


Some have also used the Greddy Type-S, in DV configuration. It's twice the cost, but people said it didn't leak. I had mine leak. I've also tried a HKS SSQV, the different types of DV's (Forge, Bailey, Stratmosphere, etc), and I personally like the Forge 007P the best.

 

A cheaper alternative would be to uprate the Comptech dv with Audi's 710N (06A-145-710-N) Bosch DV. This is used on the 2.7T S4 and the 225 TT, which both boost 12-14 psi stock. These are also used on the turbo 911's.

You can buy this at any Audi/VW dealership, but would be cheaper from aftermarket tuners like ECS Tuning. However, if you go this route, it's recommended to install it in "reverse".

 

Thanks gary! This is great information for Comptech owners.

 

The Turbosmart Kompact (bypass version) is an ideal drop in replacement. Or you can use the vent version and a BOV.