I have a 2003 g35 sedan. I was thinking about getting the osiris tune for my g but i heard it is not possiple to do with this model year. Is this true and if it is, is there any other tune i am able to get?

 

About half of the 2003 sedans are tuneable, the other half have the old style ECU and are not. Only way to guarantee either way is to look at the physical ECU and compare. If you have the old style ECU you are boned. Nothing we can do. Feel free to PM me any questions...

 

I take it, all the coupes and 350z have the tunable type ecu?
Any reason why some of the sedans have an older style?

 

That is correct

You would have to ask Nissan...

 

Let's begin by telling you, "Welcome to G35 Driver"! Any tuner would be glad to give you the information you're looking for, contact them sharing the necessary data. Before spending those big $$ on a tune I suggest your completing all the breather mods for better results!
Gary