Nice car man, I'd upgrade to to 2 1/2 or 2 3/4 just to smooth out the flow a bit.

 

ok so im gona order them tomorrow and all i have to do is jack up the rear make slits in the bushing put them on and thats pretty much it. but isnt the center of the bushing metal or is it all rubber?

 

It is a sleeve that the bushings slip onto and holds it all together. You wont need to use the sleeve.

 

back pressure is required to keep a car from burning valves.
the turbo itself provides enough backpressure to keep your valves safe, after the turbo,
the less backpressure you have, the better...
the best exhaust you can run as far as power is concerned is straight pipes
then as high a flow as you can possibly get.
most people simply go with 2.25 or 2.5" because if you are running a CAT, and resonator, the extra .5-.75" wont make a difference.
and simply put 2.5" piping is cheaper to buy then 3" pipe
I have the high flow manifold/k04/testpie, and am getting custom exhaust fitted on as soon as the funds are there....it will be No resonator, and a high flow muffler, the size of the pipe will be determined by my budget.

as said before though, with a k03/4 2.5" is plenty big, because these turbos simply dont flow enough to overwhelm a 2.5" exhaust

 

Well that is true when looking for "max" flow, problem is that the small K03/k04 internal wg turbos like back pressure to produce low end tq. Have to remember that if you reduce back pressure at the back of the turbo you are also reducing back pressure for the internal wg too and as we all know the exhaust will flow thru the path with the least resistance, this means more of the exhaust will get thru the wg once it has opened and this adds some lag and decreased tq. So bigger and less back pressure for a internal wg isn't always better and there is always a loss for another gain, no such thing as a perfect thing.

Now with a external wg it is different, because you can reduce back pressure to the back of the turbine wheel without changing the back pressure at the back of the wg. This means more exhaust wants to flow thru the turbine wheel vs going thru the wg.

 

thanks for clarifying mike@dth

everything i have read says "no back pressure for turbos"
but they never specified internal or external wg.....I wasnt aware that they had different back pressure requirements.....do you have any illustrations? im having a hard time visualizing what your trying to say (probably cause its the middle of the graveyard shift, and i dont feel well tonight..... .... ) pixxors would be sweet though

also, as a side note, a few months ago, i had my exhaust crack wide open where my cat bolted onto my turbo...the flange had rusted, i drove the car like that for a few days till i could get it to the mechanic, and i seemed like i had as much power then as i do now, and im k04, manifold, AND giac chipped now....i could be wrong, but it sure as heck felt REALLY fast, with nothing after the turbo....lol

 

Here you go.




Picture in the top right hand corner is the discharge side of the K03. As you can see the wg and exhaust wheel exits are right next to each other and in the same housing. If you decrease the back pressure in that area you reduce the resistance for the exhaust flow on both paths. Since the exhaust does not need to pass over or thru anything once the WG opens more of the exhaust flow will pass thru there because it will have the least amount of resistance. This tends to be the reason why a K03 will lose bottom end tq and gain top end.

At that point your car would feel faster up top, but down low would feel like the turbo comes on a little later.

 

so how big piping should i go after the 3in tp? and i bought the bushings and it keeps the rear from sagging but it still spins the tires......my 60ft was horrible 2.4 seconds but i made the power up top 15.08 at 94mph!!! what could i do for more
traction?

 

Some drag radials might help get more traction when the tires do lift a little. Only other thing you can do is add more weight to the front of the car to keep the nose down during a launch.

 

did the test pipe turn the check engine light on.