so far the 03/04 Cobra is the only one to come with IRS, some loved it some hated it. Drag racers hated it and swapped a lot of them out for the regular 8.8 rear ends. Not sure about the shelbys as far as IRS goes I dont really follow those as much b/c they are to expensive although I wouldn't pass up the chance to have a Super Snake if the option ever presented its self lol
I was referring to the 4v. They didn't only come in cobras. 03 & 04 mach's had them to. It was practally the same as the n/a cobras of the 98-01 cobras. They had slightly different cam profiles and head designs. For the money I spent ordering my 2013 sti I could have bought a boss but living in Alaska that's unpractical as a year round car. That's why I traded my Mach 1 for my lifted f250 diesel.
You are correct about the IRS. Only the termies have them. A guy I work with is rebuilding his cobra with a solid axle. He has limited the IRS and can't get any more traction with it. Before he tore it apart he was running low 9's and still drove it on the street.
in stock form a 2V did not put down 270-285 on the dyno. I think your mixing it up w/ the 4V Cobra which was rated at 305. If they were putting down 270 on the dyno then they would have had around 320 at the engine not 305 which is not uncommon for ford to underrate performance especially in the Cobra's. The 2V 4.6 probably put down around 185 and 220 TQ. Even guys with the full PI Swaps were putting down less then 250.
it was mostly b/c of the lack of aftermarket support. All these years later they are now just getting other cylinder head options. For a long time the only option was the PI swap which was a better flowing head and intake from ford that they put on the later 4.6's but it was still no huge power jump like going full aftermarket like with trick flow. The 96-98 2V 4.6 was a step back for ford but also paved the way for the new 5.0 which they got completely right. The 96-98 Cobra 4V was a nice engine but the 2V just never got any aftermarket love and never really took off as a performance engine. Ive never owned a 4.6 Ive had 5 Mustangs all pushrods from 5.0's (302) to 5.8's (351W) but I would not mind owning a Modular engine Mustang if it was one of the specialty ones like the 2000 Cobra R which has a 5.4 Modular. Id love to see a comparison test between a 2000 Cobra R, the new Boss 302 and a WRX/STI as far as the road course/ AutoX. The Boss would beat out all of them based on HP but I'm speaking in pure terms if handling, would be quite inserting. I think secretly Id be pulling for the 2000 R just b/c its such an awesome rare Mustang. My friend Mike has one I envy him every time I see it, which is only in his garage b/c he never drives the damn thing lol