I want to get the helix v2 test pipes and put them on my stock 03 exhaust, does it bolt right on and should i get a new y-pipe with it or is the test pipes fine on the stock exhaust, thanks

 

Those test pipes are compatible with any aftermarket exhaust made for the 350z. They can mate with the stock exhaust also. You are absolutely fine.

 

thanks and also should i get a y-pipe with it or just get the testpipes only?

 

It's your money I don't care what you get. In my opinion, I would just keep the stock y-pipe. If you swap out only the y-pipe, you will recieve little to none horsepower gains. And it will sound almost exactly the same.

If you plan to have an all-out performance-oriented Z, then I would swap out not only the y-pipe but also the rest of the exhaust.

It all depends on how much money you are willing to incorporate into your car.

 

I did testing of the stock Y-pipe on an otherwise high performance exhaust system and found that it dropped about 6 HP.

I was surprised at the results to say the least.