my car is an 87 t2 and i am currently not running any emmisions components i.e cats, airpump etc. i am also not running the twin scroll system on the turbocharger so my question is, do i need any of the solenoid valves that are located next to the oil filler neck or can i remove them all and get rid of the hard vacuum lines that they run off of. thanks.

 

Here's my writeup for the S5. It's basically the same for the S4. Nothing you couldn't figure out in a few minutes of head-scratching.

http://www.team140.net/modules.php?n...showpage&pid=3

Brandon
BR7 Racing

 

Three of the solenoids are for emission controls (and hence are redundant), one is for the twin-scroll turbo control system, and the other is for the hot-start assist system.
Unless you've removed the flap from the manifold, there's no advantage in disabling the twin-scroll system, only increased turbo lag. You'll get better performance with it working than with it wired open. If you've already removed the flap then the solenoid's redundant.
The hot-start assist system improves starting and idling if you start the car when it's really hot. Normally that's a short time after shutdown, so everythings nice and heatsoaked. It does this by cutting the vac signal to the FPR to increase fuel pressure for a short time. If you remove it you may experince problems hot-starting the car. It's up to you whether you're prepared to live with this or not. If you are, the solenoid's redudndant.
If you've deciced you don't need any of these then you can remove the whole lot. You'll need to run new fuel lines (they're part of the metal spider) and a new vac line to the FPR. The EFI chapter of the FSM is mandatory reading for this job. All the info you need is there.