The first selection is from Eric Typpo as written in the MDSOG Newsletter a few years back. He really knows a hell-of a lot about the DSMs, so give him an email.
From testing I've done with a pyrometer, one weak point on the Diamond Stars with increased boost levels is the intercooler. Under sustained boost, it heats up quickly, heat soaks and cools down slowly. Alamo Autosports only claims a not very spectacular 63% efficiency @ 16 psi. for their intercooler UPGRADE, also implying that the factory intercooler is pretty inefficient at cooling the intake charge. Spearco makes a device which sprays fluid on the intercooler to increase intercooler efficiency, but at $125, I have always been too cheap to get one and did not have space for the tank to hold the fluid. Therefore, I decided to make one myself using the rear washer mechanism and about $10 worth of parts. To make the conversion yourself you will need:
1. About 25' of 5/32" vacuum hose.
2. A washer nozzle to spray the fluid across the intercooler. I found one at Pep Boys (Motormite P/N 47110) which is designed as a replacement for GM midsize cars. It is perfect because the nozzle is at a 90 degree angle to the fluid input which makes mounting on the intercooler shroud very easy.
3. A Whisper one way aquarium air line valve.
4. A vacuum line tee.
The washer mechanism is at the very back of the car, behind a panel in front of the driver's side tail lights. Remove the panel(s) and disconnect the original hose and attach the new vacuum hose. (squirt all the old fluid out first since it will drain when you remove the old hose). Route the hose out the car through one of the grommets around the hoses that drain the perimeter of the hatch on either side (I did it on the driver's side). Run the hose beneath the car, securing the hose to the fuel/brake lines withwire ties along the way. Remove the shroud in front of the intercooler and drill a hole as far away from the intercooler as possible (to increase the dispersion of the fluid), insert the nozzle and connect the hose to it.
The problem at this point is that the hose will continue to siphon the washer tank after it is used, so your first application will also be your last. To prevent that, I created a siphon break by putting a tee and a short length of hose with a Whisper one way aquarium air line valve at the end, on the hose at a point above the washer tank at the back of the car. It is important to create a fairly sharp bend in the hose and put the tee at the top of the bend for maximum effectiveness. The one way valve prevents fluid from squirting out under pressure, but air is pulled in to the hose, breaking the siphon after the washer is turned off. (The end of the valve that you CAN'T blow through is pointed toward the tee) Use the sprayer for a second after filling to make sure that any siphon that was created during filling is broken.
Overall, it is a cheap way to regain a few of those horsepower lost to summer heat by increasing the efficiency of factory as well as upgraded intercoolers. Spearco sells a pressure switch for $36 which could be used to make the sprayer activate automatically under boost, but I have not experimented with it yet.