Well TerryGT stock GT, with MSDS header put down 352RWHP with a rich tune (12:1) (orignially 290rwhp).
Cheb with 5.4L a compression bump, and M5 itbs sees 438RWHP.

Yours should see a substantial bump....

Holy crap Colin, you can actually do that with a leakdown tester???

Is this normal procedure for changing valve springs without pulling heads?? I seriously had never thought about this before.

i have done that on a few cars. it makes the job quick

Very normal, very common.

Valve springs, guides & seals.

Easy as anything on a Chev small block.

Cut up a pair of 944S2 intake manifolds and use the runners, DIY your own plenum system...

944 DOHC manifolds bolt up to 928 head.

Here is a 944S2 manifold bolted to a 928S3 head.
https://rennlist.com/forums/attachme...d-928-head.jpg

the hood clearance is one of the main limiting factors for us.

I think in this case, whatever fits under a 944 hood will fit in a 928 :)
Obviously the engine parts locations are different but...

A 2-v 928 spider intake would stick above the 944 hood almost 10 inches, if bolted to the 944 head.

why is that? i would think that the spider would be on its side in a 944

thats the best idea yet!! just cut them off at near the base, enough to mount some velocity stacks and cage it with some kind of box. Carl could do that easily, and then , figure out how to mount the TB and MAF on the firewall side.

im game! :)
the pressure keeps the valve up flush and there are tools to remove the keepers and put them back on. OR, you can stuff some rubber hose down the hole and then put the piston back up toward TDC to put pressure on the valve to hold it in place. i gues as long as yor rotating the engine to TDC on each cylinder, the valve cant drop very far if you are using the compression tester fitting and compressed air.

I've used a nylon jumping rope to feed it into the cylinder at BDC, then rotated the piston until is stopped. This kept the valves physically closed while the springs were changed (didn't have to worry about loosing air pressure during spring change and could leave the work for another day even if the spring was removed). The nylon rope doesn't leave anything in the cylinder either (unlike regular rope might). Yes, the springs can be changed with the engine in the car but if anything else needs to be done to the engine (perhaps to do the timing belt too), I recommend removing the engine. It will be way easier with the engine out. For me, it was not fun changing the exhaust springs with the engine in the car and neither was measuring the exhaust spring compression afterwards.

It's an old mechanics trick and so is feeding rope down the cylinder. I've done it both ways. Compressed air is more elegant, the rope method is safer (in case you loose air pressure) and gives you more room (nothing sticks out of the spark plug hole).

Well if it's just that simple, why don't you get your hand dirty and make one. Then report back.

Do i really have to answer your smart ass question?
Oh, but how about i will......... I dont have the abilities or patience to build something as intricate as an intake. ive seen the work of others here and this, not only has been done by others, but can be done much better than i would ever be able to do.
Its not a matter of "hands" dirty, its a matter of abilities, knowledge and skill.
so, if someone builds it, i will buy it and test it.
I just cant believe someone hasnt built one yet. its the MOST common modification of most all marquees, yet, we dont have a product. the closest thing was the CF intake, but incorporated a little too many custom/ (home depot) parts. ;)

Why don't you commission an intake build?

I would be game to do that as well!

I dont know why this isnt a more positive and popular discussion. heck putting a custom intake on a blown motor is more of a silly build, as you can just turn up the boost to make up for losses in the stock intake. ;).
im thinking there should be a pretty easy way to get an intake on the 928S4.
if it means chopping up a couple of S2 intakes, that would be a cheap and easy start with parts that fit our heads naturally. then, the only challenge is doing some aluminum welding of a box, fitting some nice inlets to them and putting them in a place under the hood that fits the stock MAF and an aftermarket TB.
I dont think this is impossible, or should take hundreds of hours as Greg B's intake did....BUT, i bet this can be made from near existing parts... maybe the intake runners and air box from another car also made from aluminum so it can be merged together. dont know, but there are lots of possibilities.

You definitely need to read good books on volumetric efficiency, runner length and flow when it comes to the construction of an intake.

By no means am I an expert in this, but I do believe runner length and tapering may have a lot to do with how Greg was able to create the gains he did with his setup. Hell, with any setup this is imperative to have knowledge on.