In my quest to improve gas mileage on my 93 Metro, I came across Mike's heads on eBay. They looked promising, so I figured I would give them a chance. I've done other testing for diesels before, so I am familiar with testing protocols. Testing tool used today is a G-Tech RR.
We start with a 93 Metro Hatchback, 3 cyl's of fury and a 5 speed. Breathing is accomplished with a K&N filter and a stock exhaust. I performed testing consisting of 4 runs, in alternating directions with the same weight and gas in tank, etc for proper repeatability. Then I changed the cam sproket to a +10 degree model. The above mentioned testing was performed, with repeatable results. Finally, the cylinder head was added. The specs on the head are 10.5:1 compression, economy cam, nitrided exhaust valves, valve job, guides, seals, and a port/polish. Testing again was performed. Stock runs will be represented by the black line, sproket only by a red line and both the sproket and head by the green line. The solid lines are horsepower, with the dotted lined being torque.
Here is a graph of HP vs RPM:
As you can see, power for the sproket curve was shifted lower, with the combo green line jumping up across the entire RPM band. Oddly, all 4 runs for the “sprocket only mod†show oscillations above 3800 rpm.
Here is Max Torque and HP:
Torque is up 22%, Horsepower is up 15%. That was quite surprising, considering this is an economy package.
Here is info on each run:


¼ mile times increased slightly with the pulley, but greatly with the cylinder head.
As you can see, 0-60 times are quite a bit faster with the head.
Gas mileage has gone up from 38.13 MPG to 45.02 MPG. That’s a 15% increase!
I am thoroughly impressed with Mike's products. I drive 90 miles a day to work, so this increase of mileage is most welcome. If you've been considering this mod, consider no longer!! My only regret is that i didn't do it sooner.
Next, I'll be testing this package with a +6 cam sproket.