The BDR comes standard with the OEM BMW E36 (325i) radiator. (1 row)
The alum fan shroud and 16" 2200cfm fan are fine as is.
You can upgrade to an 2 row aluminum 30% increased capacity either thru Backdraft. (Iconic parts)
https://www.iconicparts.com/radiator...efficient.html
Mishimoto MMRAD-E36-92 30% more capacity
https://www.amazon.com/Mishimoto-MMR...2771349&sr=8-1
Mishimoto also makes an even thicker radiator thats 91% more capacity than the stock E36.
https://www.mishimoto.com/bmw-e30-e3...tor-92-99.html
or CSF 3054 30% more capacity
https://www.amazon.com/CSF-3054-High...770876&sr=8-10
Also you may take a look at your crank pulley dia. most kits come with the "Performance" underdrive pulley to give a whole 6 more HP and switch to the OEM dia pulley to give you more GPM especially at idle. Very helpful in traffic.
On mine I switched from.
https://marchperformance.com/ford-sm...nk-pulley.html
To
https://marchperformance.com/ford-sm...nk-pulley.html
Last thing. If your car is an RT4 I'd call Backdraft and question them on radiator to see if it has changed from the RT3. So far I only know of drivetrain and suspension changes on the RT4.