The third radiator on my 997 did indeed have this gap, though I don't remember it being unsecure/moveable. Hope that helps.

 

You might want to look into some grills for that thing. It's very exposed and will take a beating.
I went with the rennline set for all three.

 

So, what is the real benefit for 3rd radiator on a stock 997, for the track?

 

Good question, for me it's not just the track but street driving too. I noticed after install the oil temp was 10-15 degrees cooler (running 205ish degrees versus 215-220ish degree on average) on a canyon run than before the install (with the two side radiators).

 

I also have the 3rd radiator kit from Suncoast but it came with a duct piece that is connected at the back of the bumper opening and attaches to the outside frame of the 3rd radiator. Who ever did the install forgot this piece.
I also highly recommend the grill covers from Rennline, DIY, or where ever you can get them.

 

If I recall correctly, that duct is quite flexible. A slot or channel from the duct just slide into the bumper.

 

check out the hartech report. overall reduce spikes in coolant temps for street or track.

 

I just received my third radiator kit from Suncoast last week. Getting ready to install it as soon as there's at least a small break in the weather. Hoping it will keep my oil temps down a bit in this dreadful heat we have here in the summer.

 

I bit the bullet today and went ahead and installed the radiator. Don't do what I did and forget to cut the holes until you only have three screws left to put back in. Otherwise, it's a very simple and straightforward install.
So far, it seems like it's helped some. I haven't given it the full beans yet, though.

 

I have 3rd rad installed for my 2007 C2S, no gap, however i have the Aerokit cup front cover.

 

If will def. bring the temps down and keep it down. Surprising no increased in warm up time.. took forever before and about the same after install.

 

So I've had the third radiator now for over a year, haven't felt any real difference other than I think it looks super cool that it's there and also gives more confidence while driving hard in the 100 plus weather we get in SoCal. Drove through Death Valley once at about 110 degrees and didn't worry about it. Car feels good with it and for a $200 mod, why not?

 

The oil temp with my car lowered by about 5-10F after I vacuumed out the leaves and other debris ( particularly in the outer vertical areas) of the radiators. No third radiator.