On my 17, I just installed the PM Race Package: 6-point brace; rear beam axle stiffener; and front upper strut bar. I installed an Eibach 25mm bar (see my other post) and the 6-point bar and there was a "holy crap, I didn't expect this" improvement: the car felt more solid over bumps (a thud instead of a bang), rolled less and had much less torque steer. Then I installed the front and rear braces, and there was an improvement in the steering accuracy and feel, though not as dramatic as the effect of the 6-point bar. I'm very happy with the PM package and highly recommend it. You may want to start with the 6-point brace first, as it creates the most noticeable improvement. I haven't had a chance to see how the under/oversteer handling balance was affected, and I'll report back.
Installing the 6-point bar has a learning curve and maybe I can save you some trouble. Leave in the two long, forward subframe bolts (the ones you access through the lower control arms). Remove the two front LCA bolts, the two large rear subframe bolts and the two angled chassis braces at the rear of the subframe. The two front LCAs will shift in their mounts, and with a little prying and jiggling, you can use a jack and a phillips screwdriver or drift to align the LCAs with their mounts. The LCAs have to be tightened to near fully tight, in order to pull the brace rearward into position. At first it appears that the rearmost two mounts on the brace will not reach all the way back to the holes from the removed angled braces, but by tightening the LCA bolts more, I was just able to get the rear bolts in. If you don't tighten the LCA bolts first, or you put in the large rear subframe bolts before the smaller rearmost ones, the rearmost ones won't fit.
Installing the 6-point bar has a learning curve and maybe I can save you some trouble. Leave in the two long, forward subframe bolts (the ones you access through the lower control arms). Remove the two front LCA bolts, the two large rear subframe bolts and the two angled chassis braces at the rear of the subframe. The two front LCAs will shift in their mounts, and with a little prying and jiggling, you can use a jack and a phillips screwdriver or drift to align the LCAs with their mounts. The LCAs have to be tightened to near fully tight, in order to pull the brace rearward into position. At first it appears that the rearmost two mounts on the brace will not reach all the way back to the holes from the removed angled braces, but by tightening the LCA bolts more, I was just able to get the rear bolts in. If you don't tighten the LCA bolts first, or you put in the large rear subframe bolts before the smaller rearmost ones, the rearmost ones won't fit.
