Whats the best size pipe work for me to use on my gt30 setup.....I was going to make some custom stuff out of 70mm pipe work but I don't know if that's to big and may cause the turbo to be laggy??

Or would 63mm pipe work be better suited??

As the car is at the moment it has a 70mm pipe from the TB down half way to the intercooler then it reduces into 63mm so should I just do it all in 70mm and be done with it??

Thanks Craig