I was taking apart my car for some mounts, and I took a look inside the headers. What a mess, there is like 1/4" of useless metal if not blocking, at least creating turbulence right out of the engine.

So I bought a $20 air grinder + $23 tungsten bit and smoothed things out:

Before: Notice the dark lip on the level with the flange.


After




By the way, I wanted to share my bolt setup:
The studs came out one day, and I did not want to mess with them anymore. So I bought some 10.9 grade metric bolts and nuts (~$2 each).





They are 40mm long with 14mm head, 1.25 pitch.
It now requires a 14mm crow foot to tighten two of the bolts.
These never discolor or rust.

 

Hmmm..... Good job on the pics. Did you port your turbo too?

 

Yes, I ported the turbo a while back. But I was in a rush and did not take pictures. Next time I take the car apart I'll post them.

On the turbo, I ported just the air section (impeller ?) There was some metal to take off on the side coming from the air filter and the side going to the intercooler.

Lots of metal was sticking out on the intercooler inlet (I have the Ludespeed one). Took off very little on the intercooler outlet, that was a waste of time, since the IC outlet is much smaller then the throttle body intake.

My friend who has a GrandNational says that the intercooler is constructed poorly, as it has a 90 degree turn on the incoming side pipe. He says all the GN guys have a similar problem and they pay big bucks to get IC remade with a fancy winding pipe with smooth transitions, they claim large HP increase.

 

That's a possibility, but the intercooler piping setup being run by your car is the same one being run by incredibly powerful Subarus. All you'll be doing is adding more linear inches to your IC tubing, which will increase lag and decrease throttle response. Since you seem to be skilled with the tungsten, I highly recommend porting the exhaust side of the turbo. The compressor side won't get you nearly as much gain. Also, a good mirror finish is a must for the wastegate bypass, as this will almost completely eliminate boost spike and creep. Talk to the experts at i-speedusa.com to get all of the low-down. I've gotten myself in entirely too much trouble by listening to Honda and Chevy experts, (see 6-Puc clutch kit, additional inline injectors) so go to people who make their living with fast Subies. Just my 2 cents...

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