Just a couple more comments regarding the Wagner (bar & plate version)...
Obviously with the step design the Wagner is much deeper than the OEM I/C. However, even when pushed up against the bottom of the radiator, the bottom of the Wagner is still about an inch lower than the OEM I/C. As a result, the plastic cross beam that channels air to the OEM I/C blocks a bit of the frontal surface area of the Wagner unit. In addition, slotting the Wagner unit behind this plastic piece made it very difficult to line up the OEM hose couplings. I'm sure the install can be done without removing the plastic beam, but I chose to cut it out. With the plastic beam removed, the Wagner sits flush with the plastic under tray, therefor there is no gap under the Wagner unit and air is forced through the I/C.
As mentioned above, the OEM connections are machined to very tight tolerances, so intallation can be a pain. If you go this route, here's a helpful tip... Unlike the OEM I/C where the retaining clip can be pulled partially out and it will stay in an unlocked position, the Wagner unit will not do this. However, if you spin the retaining clip 90 degrees, the locking mechanism is open. Then all you have to do is plug in the OEM hose connector and spin the retain clip back to the locking position. Give the hose a tug to make sure it is locked in. Like I said, the tolerances are very tight so getting it to lock took a few attempts.
As for performance, I am very happy with the Wagner I/C. I live in Florida so excess heat can be a real issue. In the summer time (90+ degree ambient temps) the OEM I/C would show IATs around 108 degrees on the highway. After one WOT pull through 4th gear, IATs would approach 140 degrees. With the Wagner unit, IATs on the highway (in the same conditions) sit around 101 degrees, and around 104 after a WOT pull. There is one thing worth mentioning about the step design... If you park the car after you have been driving, then return to the car within 30-60 minutes, the initial IATs will be relatively high (i.e. 120 degrees). The Wagner obviously picks up some heat from the radiator when sitting still. The temps return to normal within a mile of driving, but thought this was worth mentioning.
I would say throttle response is slightly better than stock, but not overwhelmingly better (i.e. stock is pretty good for forced induction). The real benefit is felt on WOT acceleration. Whereas with the OEM I/C the car felt like it was running out of lungs around 85-95 mph, with the Wagner the car pulls strong well past 130.
Also, the Wagner unit is very solid, much much heavier than the OEM unit, and the black finish is showing no signs of wear.
Hope this helps with your decision.