The manifolds don't creep with RPM really. But none of them run spring pressure.

But to that point, if you want to run 20psi, I don't think an FF turbo kit is going to be the right choice.

 

I always want the option to choose the map I want to run.

thanks for your input

 

I'm already running 46psi with a map proformance down facing mainfold with a PT 6766 turbo being tuned by john whalen remotely already making 830 hp on a mustang Dyno...buy since I have the full rad and ac condenser the air is some what restricted to make more power...that I why I wanted to go forward face and go a little less boost making close to the same power.....well that's what the aim is anyways.

 

my map proformance twin scroll t4 mainfold which is NOT a FF mainfold don't creep a bit...always hits the gate Target on gate pressure when I did test it.

 

You're not going to gain much going to an FF manifold. You won't see it in the dyno anyways.

What size gates are you running? The manifolds I referred to were all running 38mm Tial. So if you're running larger gates that could help.

The worst ones are the manifolds that run a single 44mm. I've seen those not run less than 35-37psi with a 6466, regardless of spring lol

If you're going to change turbo kits, id suggest a better turbo also. The 6766 is a dinosaur. A gen2 6870 will out spool it and make more power.

 

ya sorry forgot to mention in running 2 tial 38mm wastegates .

it's 6766 gen 2 which was I think updated and rated at 935 hp...so it was perfect for me.

ya so I'm happy with 830ish hp where I'm at rite now all I want is less boost while making at least the same amount of power.

 

That's not really how it works once in you're in that 800+ range unless you go to a really large turbo (72mm+), which then won't spool well. And probably won't even really run "low" boost like you want.

But I'll tell you I have a car here that make 845whp at 43psi with a gen2 6466. So either your setup isn't quite ideal (cams, intake manifold), or that turbo isn't as great as you think it is and a PTE gen2 6870 would help,

 

​​​​​​well my cams are gsc s3
intake manifold is meh... race version which I believe was made out of sheet steel.
engine is made my whalen R&D which includes a oring'd block

ya also I don't trust the mustang Dyno I get my car tuned on...it's tells super low numbers...like my friend had his civic tuned on it and it gave 680whp and after 1 month he got it dynoed again on dyno jet and it gave like 730whp on the same setup.

okay anyways let's see how the mainfold comes out will be posting for sure since no one else is lol.