This is the first toyota engine ive ever owned, so i dont know a lot about them, and i cant seem to dig up a lot of technical data either (maybe im not looking in the right places.) anyhow, i am pretty familiar with the mazda engines, and there are a few things you could do on the newer engines to maybe get a little more throttle response, and MAYBE a HP or two. so if anyone knows much about this on the xD, follow up...

1. mazda intake manifolds have baffles inside the intake runners, which basically look like a smaller throttle plate just at the end before the head. they are closed during cold starts and cold idle, but even after the engine warms up, these were only capable of opening about 90% of the way. these could be removed and would drastically reduce the 'blockage' within the runners. only trade off was a slightly rough idle when cold. and obviously these wouldnt be a problem if the dynatek intake manifold actually exists and is put into production.

2. balance shafts - anyone pulled their oil pan yet? its usually as easy as removing the pan, the shaft assembly, and blocking an oil port. definitely helps with throttle response while giving only a little more vibration in the wheel at idle (was not noticeable at all on the mazda3).

3. timing - mazda motors had a timing sensor located over the bottom pulley of the timing belt. it was held on by a bolt and a bracket which had a groove. you could slide the sensor along the groove to slightly adjust timing, about +/-2 degrees max. might help you get a little more power out of a higher octane fuel, depending on how smart the ECU is.

and i know that if you could apply all of these to this motor, the most you may get is some improved throttle response, but they could be worth a try to squeeze just a little more out of this car until the aftermarket gets a little better.