Yeah they'll have been fitted after the fact. Explorer and GT40 lowers have the same bolt pattern/port arrangement so it's just a bolt on. Thing is though a Cobra upper actually flows better and then you can extrude hone it for even more flow. A GT40 upper cannot be extrude honed.

Pete.

What benefits did you see in fuel economy/power by having your injectors sonically cleaned? Mine have about 190K on them so probably need looking at....also do you have an idea of price? Is it worth it?

Cheers

Unfortunately I can't remember the price as they did it at the same time as a lot of other work I was getting done. I do remember though that they would give me a cheaper price per injector if I removed them etc (obviously they didn't then need to charge for removal and refitting if I did that) The reason I actually did this is because I have been having a lot of problems with the car running poorly. This didn't end up fixing it though it happened to be the chip that the car had in the ECU I think it was either faulty or just not connecting correctly in the J3 port. So I can't really answer the fuel economy / power question either as taking out the chip made it feel heaps better. It was way more responsive and also has a lot more top end as well whether that is from the injectors or the chip I don't know. Only had the car for about two weeks like that before I had to put it in for a full respray and so I haven't been able to really drive it that much. Short answer is I reckon do it and also get the throttle body and MAF cleaned while you are at it.