I have been told it was the catalytic converter however i was suggested to check other things ( vacuum leaks etc) that could be causing this code.

What are some things to replace before i change the cat?

If my last option is to change the cats, should i get a straight pipe instead?

 

I'm thinking P1273 would be more for leaks. P0420 & P0430 is a code mostly stemming from a leak in cats or test pipes or test pipes in general.

 

Straight pipes won't pass emissions / inspection... at least here in VA. Jack up the car if possible and check the cats, and sensors.

 

On your '08 Z, cats are warranted 8 yrs. / 80k miles. Check with your dealer service dep't. Heads-up, they may want to replace sensors first.