I prefer to buy and modify, rather than from scratch.  OEM or aftermarket, will do, if it is good aerodynamic design, and can resonably be modded to a Jensen Healey. This is a rear radiator/camback, tailed car. Any ideas ?  Thanks, roverman.

So you're looking for something sortof like this?


I can never remember... is this for a racecar? An autocross car? A track day car? A street car?

Mostly street, some track days, even less slalom. Can I get one about 3 feet shorter ? I like "some" of the oem stuff, but maybe the're more for looks than effectiveness ? Not nearly as developed as Ferrari 355,(no wind tunnel available). I do plan to use a manometer/etc.   Thanks, roverman.

Here ya go Art, it's our generic diffuser for F5/F6 cars.A diffuser as short as you are talking wouldn't do much .
Dave

Check out the various styles being bolted under the Lotus Elise.

I would like to find "vortex generators/applicae", miniturized Wheeler vortex generators, that stick-on, in sheet form. This should make the diffuser more effective, by keeping the negative pressure layer, better attached.  Where to buy ?  Cheers, roverman.

Sorry Art , I don't know of anyone using vortex generators on a diffuser,  in fact the diffuser pictured on that Mazda is a huge drag inducer because of air becoming unattached and  gathering up in the wake at the top rather than exiting cleanly, that car is obviously a solo car, solo cars run  huge wings at stall angles and that one in particular has a huge air dam on the rear these things only work when you are trying to develop the most downforce you can for short courses (parking lots) and they usually have enough power to overcome the horrendous drag, In real racing Only Formula one could sport  the drag deficit they do because of the power to weight ratio they have.
Dave

Ok, But does the concept have merit ?  Seems like correct ones, will keep air attached longer/more effective ? Three feet "behind" the car, not an option. Considering replacing trunk floor, with possible diffuser, "under"radiator inlet,(rear radiator outlet through camback grille). Cheers, roverman.