I need help deciding which one to choose.

 

Only cause that's the way I went I heard the was a porting change made a t Z1 so went M370. Happy with it

 

I have the VQ35HR Plenum what you call the M370..i couldn't see spending 600+ on something I could do myself for 150$...
and I also run my stock Plenum that has been modified by me as well..kinda like the Z1 but have yet to dyno it..to see what has more gains..
but as of right now the VQ35HR Plenum is what i am running and am very happy with it

 

https://www.myg37.com/forums/engine-...lenum-mod.html

Or

https://www.myg37.com/forums/intake-...torsports.html

Are two threads you should read thoroughly. The first is what helped me decide which manifold to go with. I chose the m370 because it has more usable power mid range vs z1 which showed its gains at the top end. Now the second thread is another guy providing a good service to the forum by porting the parts for a reasonable price. Hope this helps.

 

I have the M370 as well and have no complaints and picked up very nice gains. I wonder what would happen if I ported it?? I guess I am going to have to find out..

 

Z1 has been porting the VQ35HR plenum
from Z1 on the g35 site

We have netted anywhere from 3-7rwhp (after hours of tuning) with the mod, but see the bigger numbers from clients that have installed cams on the HR engine. We are also honing the lower manifolds for better flow.