The 1/35 MRC AH-1W is one of the most accurate kits around -- as long as you are building a pre-NTS bird (I think you mistakenly typed NTF).
NTS is short for Night Targeting System, which was introduced to the fleet just prior to Desert Storm. The MRC model is based on a non-NTS airframe, so it is an excellent representation of any AH-1W from the 1980's up until shortly after ODS.
For the short answer, basically, NTS upgrades introduced new navigation gear, radios, and the ability to fire Hellfire missiles. These are all interior, electrical component changes. However, there were some significant exterior changes as well. The FM (sharkfin) antennas atop the engine nacelles were removed, and the comm antennas are slightly different. GPS antenna was added.
But most noticible is the new nose section. A new FLIR turret and laser ranging system was incorporated to the nose, making it look much bulkier than the previous system. These larger components projected back into the gunner's compartment, and necessitated a reduction in the size of the gunner's canopy.
This is the new nose that the Cobra Company set represents. The set also includes the new electronics in the gunner's cockpit, and a beautiful cockpit tub and intrument panels in general. The update set also includes the newer AAR-47 'fish eye' plume detectors installed in the very late 90's / early 2000's. There's more, but the question really is more about era, as opposed to accuracy. The MRC kit straight out of the box build up into a very fine early AH-1W, but if you're looking to model a late 90's or OEF/OIF bird, you need to look at the Cobra Company update.
Keep us posted
--Andy