I have the Jacobs Ultra Team (ignition, wires, coil) Milage master on my Sonoma. I have had it for about 4 months now. Simple to install the wiring but where do I put this thing 4x3.5x6 inches??? Kinda big when you got ABS, AC and all the smog crap under the hood. When I was cutting my fenders I had to take the hood off and pull the rear part of the fender out. Thats when I finaly found a place to mount it. Total price i think was $375. MY opinion, well mixed. I do get a moderate seat-o-the-pants boost in power an any RPM. When you mash the go pedal it really moves (very noticeable). I once got about 23%(45 miles) more milage on a tank long open driving. City driving took away about 10% (20 miles). So it does whats advertised just not all at once. When I bought this I did the numbers and figured it should pay for itself in two years from gas savings. Unless you commute long miles every day, don't count on gas savings. I think the unit is good for open driving and a performance upgrade but if your looking for saving money while city driving, look elsewhere. If you want more info on this get Jacobs ignition book. Excellent tips and ideas told to you in a way evin I could understand. Talks about timing, NOS, electrical, and the entire ignition system. Evin if you get the MSD or whom ever, his book is informative reading.
-Troy 'WeaZle' McCarty