I recently completed installing a ProAlloy (S111 proRad-FP) radiator in my '06 Exige. Installation was pretty straight forward. Though, fiddling with the condensor tabs and fasteners (located on the front underside of the radiator and accessed through the grill opening at front of the crash box) was the most time consuming and annoying part. I would recommend doing a search about radiator installation and, at minimum, reading the following LT thread before proceeding with your installation:
In addition to bman6074's tips, I came up with some additional tips that were helpful in completing the installation with the least amount of brain damage:
Condensor tab fasteners - as per bman6074, I also found it necessary to slot the radiator so that it would slip into place. Also, I placed the washer and nut onto each fastener and used a small piece of masking tape to hold them in position before sliding the new radiator into place. Once the new radiator was in position, I reached into the opening under the radiator, pulled off the tape, and spun the nuts down as far as possible before finishing with a wrench. Using tape to hold the preinstalled washers and nuts in position eliminated the brain damage of installing the washers and threading nuts blindly in a tight space.
8mm fasteners on the radiator mounting bracket - at the factory, Lotus installed these fasteners with the washers and nuts on the underside of the mounting bracket pinched against the foam. I reversed the fasteners during reinstallation by sliding the 8mm hex-heads into place coming from under the mounting bracket and attached the washers and nuts from above. This eliminated the hassle of sliding washers and nuts between the mounting bracket and foam while threading the 8mm hex-heads.
Foam rubber replacement - the radiator foam rubber filler strips on each side of the radiator (on my car) measured 1.25 inches square by 9 inches in length. I noticed that the foam fit somewhat loosely with the new radiator as compared to the OEM radiator that I just removed, and that is because the ProAlloy unit is just a tad less wide (maybe 1/4 inch?) and the foam may have shrunk over time. So, I added a strip of black rubber foam (made by MD, 1.25 inches wide and .375 inches thick, glued into place with 3M adhesive - both found at Lowes) to widen the OEM rubber filler strips. My plan was to glue the rubber filler strips to the sides of the fiberglass radiator shroud rather than to the radiator as the factory had done. The MD rubber came with adhesive already applied to one side and covered by a paper pull-away strip, and I positioned the MD rubber with its adhesive side against the radiator shroud. Why? I figured the glue would not get baked hard and dry by the radiator that way as had happened with the factory installation. With the radiator already installed, I came up with the "zipper" technique to glue the filler strips: I pulled the MD protective paper back about 1 inch, attached a loop of duct tape to each side of the paper strip and neatly glued the duct tape flat against itself (loop was about 12 inches long once in place), folded the duct tape loop back against the MD protective paper, slid the foam filler strip into position on each side of the radiator with the duct tape loop hanging out, and removed the MD protective paper with a gentle and steady pull. The result was that the rubber foam filler strips were neatly glued into position against the radiator shroud without bunching up, any smeared glue or brain damage.
Refilling the coolant - I used my trust Gates AirLift to pull a vacuum and refill the coolant with NO HOSE BLEEDING required in about 5 minutes from start to finish. There is just no other way to do it IMHO. Knock yourself out if you want to screw around burping and bleeding the hoses for hours on end.