I don't think using deionized water would be a good idea. It's been a few years since I have dealt with it but I think DeI water has a Ph that is either basic or acidic. Either one can be rough on your finish over time.

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'96 F-150 302
Hedman Hedders, Catco Cat., Gibson Super Truck, K&N F.I.P.K.

 

Any home center (Home Depot, Payless Cashways, Ace Hardware) will have 10 inch filter housings and a variety of filters that you can add garden hose bib threaded fittings to. The tough part is to get a filter that will clean up the water specific to your area.

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97 F-150, 2WD, Reg Cab,Flareside,Dk Toreador Red, Windsor 4.6, Magnecor 8.5mm wires, Bosch Plat +4s, 3.55 LS, EGR Bug Deflector, Retrax Bed Cover, BedRug, XL Full Length Running Boards,EGR Fender Flares, Air Aid Kit, Gibson Single Out Cat Back, Superchips, TransGo Shift Kit, Hellwig Rear Sway Bar, Hellwig 2500# Overload Springs,Energy Suspension Polyurethane Front Sway Bar Bushings, 265 70 16 tires, Rancho RS9000 shocks,Expedition Center Console