How restrictive are std headers ej20
 

As above really at what power will the std headers become restrictive?

I wondered this....
I know a lot of people change the headers/up pipe to tubular ones, GT spec etc. But I don't know if that's for the sake of changing them, or because they genuinely needed to when they reached a certain power level.

you can argue the standard headers are restrictive at stock power, you'll gain some spool and a little bit of power if you have them ported a little along with the uppipe.

Ported headers good up to 380/400.
After that, go tubular.

And get a Harvey trick up-pipe.

Ahh crikes that will see me happy!