Welcome to Thumper Performance!

We are dedicated to increase the performance of our MC and MCS through expanding new ideas and prior experience from our own engine building and racing experience. We use what we sell and modify. You can count on the products you see on this site to have been tested and installed on our own cars. The gains of power are proven on the Dyno. We try to keep it as real to the actual driving conditions as possible. The cooling fans at the dyno are primarily to cool the engine and NOT used to super cool the I/C, which will give an incorrect “actual” H.P. in street conditions, where the airflow is poor.

Although we are primarily interested in Performance Cylinder Head Modifications, we will look into other mods also. When we find a procedure or an item that will increase the torque and the power levels, we will offer it up. However, we will try to be a little bit different, as we will share all the data we have noted on those items, from OUR own cars, with actual road tests (SOP meter) and the Dyno sheets. Our intentions are NOT to try everything, but to try and decide the best bang our buck!

Our Ported Cylinder Heads reflect this idea. Power to keep the daily commutes fun and exciting. Keep the low to mid range for the stop light to stop light drive and still have all the additional power needed for the higher rev aggressive driving we all love on the occasional Track Day.

Our Stage 1 Street Performance Heads are modified to work with the basic mods used by most MCS drivers - the pulley, exhaust and CAI, yet still allow more power when a camshaft or other future modifications are added. We keep the stock valve size with a 5 angle performance valve job (flow cut on the valve) to maintain the good street manners, and yet with the correct port work in the runners, bowls and throat, it will pull hard till you reach the red line when on boost! Velocity is the key to a small displacement engine, as we are NOT on boost all the time. And if the “off boost” is where we drive 70% of the time, then the higher flow numbers of a “larger valve” head means slower moving air and a low to mid range loss where we don’t want to lose it.

We do know that there are racers out there, and we do also make a head for the track and seriously aggressive drivers. If the revs are to be at the 4500 and higher range on full boost and yet still need power out of the turns, then we offer our performance “Big Valve Head”. We will need the Cam specs and the rev intentions to insure the heads are at your needs.