I havent ever heard of this "inexpensive" mod. can someone clarify this for me real quick ? thanks

 

go to scoobymods.com and run a search, it'll be there.......it's a cheap mod...mixed thoughts on it though.

 

This is the best picture tutorial on how to install the 3/16th mod that I have seen.

http://www.scoobymods.com/forums/sho...ghlight=3%2F16

Just be sure that you get the right part The first time that I did this, I misunderstood and put the 3/16th in as the 3 way (T) instead of the 2 way that you are supposed to do Also, another word to the wise. If you pull the hoses (I would recommend this so that you are not spending half an hour leaning over your engine bay, make sure that you are putting the hoses back in the right place. There is a hose with a restrictor in the line (I hear it is brass) that you want to have back in the right place. Apparently you need back pressure there or you never get over something like 9lb of boost. Also, if you have never worked with these lines before, I have found that a little dish hand soap makes it a TON easier to put the 3/16 peice in place. If you dont use it, it is an ordeal to get into the hose.

 

Make sure you have a working boost gauge before you do this mod. I made the mistake of doing this mod without a boost gauge. I could not really tell any difference with it so I left it on. At the drag strip the car only did the mid 15's. I went and had the car dyno'd eventually on an all wheel drive dyno. I have a turbo back exhaust as far as mods. The car only put out 144hp at the wheels. Attached a computer to the car and showed only 8 psi on full boost. Took it to the dealer and they suggested that i replace the stock exhaust and then bring the car back in. I had installed a boost gauge after the dyno. I replaced the 3/16th with the original piece and took the car for a test drive. I was now getting boost up in the 13-15 psi range. At the track i started to do runs in the mid 14's. All this by replacing the original factory piece. So maybe some people have good luck with the 3/16th and other do not. I did not.

 

I did it wrong the first time, and actually got more performance out of it...but it was also spiky. Would jump up to .11mPA, then even out at .09 in most gears. This was a very large boost on my stock car from the .07-.08 max boost (high altitude causing slightly lower boost levels on the gage). Anyway, changed it out for the correct 3/16th, and it has dropped down to .08-.09 steady boost. No wavering and spiking when done correctly. This mod has been in for about 5k miles so far...so I am assuming that the ECU has already made appropriate adjustments (dumb smart cars )

 

This is the first thread I have seen with anyone getting any change in third or fourth gear boost levels or adverse effects.

Mod can be done easily leaving all the hoses in the car.

This mod is for cars that have no boost mods. I believe the ABC with UTec and others put a 3/16" T-fitting in this exact same spot to feed the bleeder valve so achieves the same flow through that hose as this mod (plus adds the bleeder valve). I also believe most BC eliminate the participation of this hose in boost levels entirely.

The restrictor in the 03 is plastic.

After an ECU reset/relearn - I have found exactly what was claimed when I first read about the mod, boost comes on slightly ealier and holds better and longer. In first and second gear I am getting close to maybe .01 more boost.

It is a free mod that at the minimum when done right definitely should not hurt anything (Every UTec install [100s, over a 1,000?]has the same mod effectively.) and at the maximum gives a bit more turbo response.

Why would anyone even think of driving a turo'd car without a gauge? Don't do it even stock - it is too valuable an indicator of potential trouble.

 

Yeah and don't replace the T further down the hose with the straight through 3/16", I suspect that is what happened with those experiencing lower boost pressures. Doing this basically disconnects the boost solenoid and without a BC, I think it keeps the wastegate actuator open.

 

I am not sure if Subaru used more than one type of restricter or not. My 03 WRX wagon had a plastic one and all the pictures I have seen of this mod so far have been plastic. Do you have a picture of the hose and area around it that the restricter came off of?

The restricter is replaced with a straight through coupling. Another restrictor would not accomplish what this mod seeks. The idea is that the boost solenoid can tell the pressure in the system faster and cleaner, then communicate to the ECU and receive instructions on its cycle faster. The solenoid's awareness of the boost level in the system is more stable than with the restricter. The restricter on the solenoid is like a slight pinch in a boost gauge hose - the gauge will likely be delayed in reporting actual boost.

I only get slightly more boost from this mod, but that may be as much because of the ECU reset and I taught it better than when I first got the car. So maybe what I should really say is that I get slightly more boost AFTER this mod - it likely is not related to the mod itself since the mod is NOT intended to increase boost. Boost can only be increased by getting the solenoid to cycle less (ECU mods) or removing the solenoid from determining boost levels by utilizing a BC. The only claim the mod can make (and that is still argued everywhere) is that it increases boost response and boost holds better.

We are at the same altitude, so as long as you are using 93 octane you should be able to get slightly below .1 in third and fourth gear pulls. The best fuel you can get followed by an ECU reset and aggresive driving while the computer relearns may get you slightly better max boost.

 

LOL, at least now I know where this mysterious brass coupling is located and the next time some one mentions it I can redirect. Come to think of it I don't think any write up includes this useful piece of information.

The restricter being replaced is on the passenger side of the intercooler.

And should definitely be plastic. It is black and the hose would almost look to even have a restricter in it were it not for the exterior of the hoses being different.