Moto East NC MX5 Miata/Duratec/MZR Intake Manifold Results


We have published some numbers in the past, but this time we put to test a very popular combination–our stage 1.5 cams and the intake manifold and an easy to get off the shelf header (Goodwin 1.8″). The results? Outstanding! We picked up around 24 HP at 7000 RPM and 18 at peak power versus a car with just cams. Compared to 2.5 without cams, we picked up 50 WHP at 7000 RPM. While we always strive to back up our products with significant R&D, it is no small feat to make 10 horsepower NA, let alone this much. This is one of the few products that will consistently increase output on a naturally aspirated motor. Many companies have made intake manifolds/ITBs and have had more issues than improvements–we are very proud to have accomplished something that works this well. 202 WHP NA without needing our large primary header–this is a simple Goodwin Racing 1.8″ unit that costs only a fraction of that and bolts up to the stock exhaust. While the gains are more substantial with our 2.0″ header, the cost to benefit makes more sense for most folks to stick to the small shorty header, unless racing is the exclusive use. Note that we picked up another 6 HP with our full 3″ CAI that is specifically designed for the intake manifold, though the standard 2.75″ intake still works quite well.

Cam equipped baseline versus the intake manifold, 3″ CAI, and the same cams. There will be a torque drop below 4200 due to the runner length, but at race engine speeds there is a substantial gain.


Below is what a “bolt on” 2.5 does compared to our 2.5 with cams, 3″ intake, and intake manifold. At 7000 RPM there is more than 50 additional HP and 40 more TQ. Very few platforms can see gains like this without forced induction. Because our 1.5 cams add so much in low end torque, there is only a minimal drop below 4,000 RPM compared to a stock 2.5.



And on this graph you can see what our large primary 2″ header does in comparison to the 1.8″ Goodwin off the shelf unit. Both cars have the same cams, the same intake manifold/CAI setup, but the red (higher) plot uses our $1649 header and a full 3″ exhaust. Pricey, but this is the only way to get the last bit of power out of the car using stock compression.


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