An excellent upgrade on its own, and a perfect match to our performance 3400 cylinder heads. Both manifolds are thoroughly cleaned and fully ported, netting the most airflow while retaining the runner taper and improving the wall texture. A 65mm throttle body upgrade is recommended, but not allowed in some racing classes so the option is there to keep it stock. 65mm is default.
The porting itself is based on many years of flowbench testing, racing analysis, and dyno results. The current version are the best flowing yet, but we don't have the updated dyno results to share yet. (coming 2023)
- Stage 1 is based on the 3400 upper intake gasket
- Stage 2 is based on the 3500 upper intake gasket, which has more area to allow for a larger opening at the start of the runner. This increase in flow is certainly measurable at the intake valve, and the runner taper increase also seems to be beneficial according to dynomation.
There is no core system. Manifolds can be sourced for you, or you can send us a good set. No one wants to receive a cracked intake manifold, and it might not be obvious if the manifold isn't cleaned up first.
Please contact for a current turn around time on port work. 7-10 days under normal workload when you send the manifolds.
If you would rather not pay for the best porting and performance but still want a reconditioned manifold set that is setup for a 65mm throttle body and some amount of porting/cleanup work, please contact for more information.
