The great GReddy-style plenum How-to of 2007!

By Kym.

I think I'm going to be the first one to actually post pics on how to install these eBay plenums. Enough talk already! Pending everyone's comments, I'll create this as a thread in the tutorial/how-to section.

To clear up all the BS circulating on these forums about them being no good etc. I bought this thing off eBay a few months ago, for science, oh and to clean up the engine bay and see the actual driveability difference between the two.

* Plenum cost $380
* Throttle-body adapter $90
* Brass nipples $30
* Fuel/Heater Host $50
* Silicon Bends/Pieces $80

Still not done yet. I need to get one bit made up first. It's for the AAC valve air-feed. Usually comes off the intake side before the butterfly. Maybe another $50 making this bit.

About $680 all up.


I took the time to replace all the engine belts, install some HID's and re-mounting my intercooler in the process, so I took my time.

Tools you'll need?

A good 1/2" Drive socket set.
A good 1/4" drive socket set.

Vice grips, pliers, insulation tape, wire brush, soldering iron, some hookup wire, loads of screwdrivers. Hacksaw, side cutters, a bench vice helps,


If i've missed anything out, or you can see anything else that I have forgotten to mention, let me know so we can make this a valuable resource.


Well, Here goes.....



Loosen and remove the throttle body, top crossover pipe and other various pipes. Easy stuff.



Yeah, I took the front bar off too to remove the headlights. You'll see why later. Yes, my front radiator support is pretty hacked up eh?



Remove these pipes below, and your washer bottle.



Under the stock plenum, there is quite a few brackets that hold on coolant lines you'll need to remove.





See the bolts below;




Remove the top coolant bleed-valve bracket.



Put the stock throttle-body onto the new plenum, for science.



Remove the AAC valve from the rear of the stock plenum




Oh, it looks like this btw.



After you've removed the top collector assembly, (see how many bolts in the pic below), YES they are a pain in the ass to get to, no it's not impossible.




Test fit the stocker fuel rail to the new plenum. Under each injector you'll find a rubber O-ring. Don't lose them!



Yep, looks good.




Stick some rags in the top pipes, so you don't drop shit in there. Remove the bottom stock plenum, pretty simple, the bolts are easy to find.



Test-fit the new plenum, I put a rag so I don't drop shit in there again.





NOW, let's get to the cool stuff.


We're going to block this pipe off. Watch.




Snip this line, pliers will do.



Stick an appropriate-sized bolt in it, and clamp it shut.



Stuff to buy:


Threaded Brass nipples. I bought

3x 6mm for small vacuum hose.
2x bigger size (to suit brake booster and cam cover breather)
1x HUGE one for underneath. You'll see later.

3 Meters of 3/8 Fuel line
1 Meter of heater hose.

Gasket-making stuff. You'll see why later.





Mmmm, nipples. (Don't try and lick them gents, they taste like shit)


Big nipple below, oh, and unbolt the coolant lines from the stocker to the new one as per the next few pics. Same with AAC valve. Not rocket science.



This is how you hook up the coolant solenoid and lines.



Don't forget to put some gasket-making stuff on here for a good seal.




The nipples go here. K.



I put some gasket-goo-making stuff on this seal too. Call me silly, but it makes sense.





Pull out the injectors from the fuel rail. Like this. A vice and big flat screwdriver helps.



Take them ALL Out. You'll see why in a sec.





CUT, saw. The top fuel feed off. You don't need it, and it looks ugly.




Then cut off the supports that hold that top fuel feed on.





I used a small set of files to get rid of the crap inside, so nothing can fall off and end up in the injectors later.




Remove the fuel pressure regulator like below, and spin it round.

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Now, remember that bit of fuel line you cut off before, let's re-use it smile.gif Remove the bracket from it like below.




Cut, cut cut!




Strap it to some fuel line we bought earlier. You only need a bit. And clamp it down.



Remember this below? It's the turbo water line that went into the back of the stocker plenum! (yes, we gotta hook it up!)



Use our bit of fuel line, and some ingenuity, and extend the water line to the nipple below. You'll see what I mean. It's hiding.



Back to the plenum, Plumb the heater hose to the bottom, and cable-tie it to keep it neat.



Replace the gasket to the head. Like below. Notice our newly patched hose at the back left there?



Slide the plenum on, like so.



Looks pretty huh?



WIRING and beyond!



Cut these two loom connectors off, ONE AT A TIME. We're going to extend them out a bit.




Using some hookup wire, and a soldering iron, extend the wire by about this much. But not too much, you don't want it hanging in the way later on.




And tape them both up again. Like below.




Bolt the plenum in now, you'll need about 5 new shorter bolts for a few of them. You can't re-use the stockers. They're too long.


Looking DOWN the top of the plenum, there's the water line solenoid you'll need to connect to the plug again. It's hard to get to.




Yeah, its the blue one.




Stick the O-rings in the holes, like so.



Bolt the injector rail back in. THERE ARE LITTLE NYLON SPACERS UNDER THE BOLTS. Don't lose them!

The top cam breather pipe goes into the big nipple at the rear of the plenum. Add fuel lines to the rear (pictured below) This comes from the fuel filter. It's the feed-line.



See how we spun the fuel pressure reg around? There was a reason for that. So it didn't hit the injector!



Clip on the FRONT fuel line, which is actually the return line.



Put the brake booster on the back to the nipple. You'll need to cut the hose and make it a bit shorter to fit.



Put the injector wiring harness back on, and put the main loom back over. Don't worry, you can't screw it up.



This is how i did the throttle-body, using stock cable!



A few more pics coming soon of the finished product.

The finished piping.


The plenum along the side;



This is the AAC valve air input.



Don't forget to plug in all the wires again.




I welded a piece of galvanised tube to the side of the pipe for the AAC air input (without this your car won't start, FYI) and plumbed it into the pipe just before the TB.



Closer-up of the welded piece of tubing onto the side.



Underneath the whole thing.



Nice stealth location for the BOV too I reckon.



The finished deal.







End summary. Horsepower gain? haha NO. Throttle response gain, +40% pedal feel. Very nice. Noticable lag/reversion decrease.

Thanks for reading!

Great post mate. This is what the forums is all about.

Top effort there mate Great write-up, looking forward to pics of the finished product

Wow awesome writeup! Nice work!
Pictures tell a thousand words..
Referenced for future.

Move and put in DIY thread?

Nice writeup mate, how did you find the quality of the eBay item?

nice work kym, be interested to see what difference it makes

nice work mate. definitely going in my bookmarks.

Excellent work mate, i would just be a bit weary abou that throttle cable, from my experience they have to line up well to work properly.

Not too bad, the water galleries all line up, everything was decent. Let me just say I think i got "one of the good" ebay plenums (judging from previous pics people have posted)


I'm not aiming for hp, but for throttle-response mainly. I think it'll make quite a bit of difference



Noted I guess my first drive will tell the story.

I copied most of the hookup layout from my gf's car. She has a genuine GReddy plenum on hers, always good to have them side-by-side for comparison.


Stay tuned for more soon...

Great write up.

Interesting to see whether its worth it or not