i have a 2005 sti with a 3 1/2 aps tbe and a cai i was wondering which is better for my setup should i go with a solid or flex is one better than the other or is it prefrence? and which pipe (manufactures) would be best for my car ?

 

U.S. market (USDM) STi models do not have a pre-catalyst in the uppipe, only the WRX up through 2005 model year. New for the WRX in 2006 is a catless upppipe.

Not much to be gained from swapping out the factory STi uppipe for an aftermarket unit unless you are planning on much more mods than what you already have.

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"…axles of evil…" - george w. bush

 

Its true, if there is nothing else you want to do to your car, and have the money - go for it. If you do go for it, go with a flex, it will help to prevent exhuast leaks. Oh, removing and replacing the uppipe requires you to unbolt the passenger side engine mount and lift the engine so that the flange can get past the block and frame of the car... massive pain in the ***. I will take off and put back on my headers 3 times before I do the uppipe again!

 

i have a 2005 sti with aps 3 1/2 tbe aps cai walbro fuel pump and a reflash what would you guys suggest my next mod to be ?

 

Turbo back exhaust, forget the uppipe, you don't need it, it'll do almost nothing for you performance wise since the uppipe in the 2.5s' don't have a cat.

 

Not true at all. I have replaced my up-pipe several times and I have done it both by leaving and removing turbo. You can do it just by removing downpipe and header,Tmic. It takes me a couple of hours to do it.

 

What up-pipe do you have? I assumed all were the same. I have a PDE and it said in the directions to loosen the engine mount and jack it up about an inch. I tried to pull it out with out lifting the engine... I didn't try for more than 15 min or so but gave up trying to solve the angle puzzel and went for the engine... It made it easier to remove.

 

I had the stock up-pipe, switched it to a helix, and back to a stock sti after it broke. They are all the same. I have all aftermarket products so it's easy to remove the dp and the header. To save a little time I used some wire to hold the turbo in place and put the up-pipe through the bottom of the car first after removing the header. my up-pipe didn't come with directions however

 

....nobody in their right mind would mess with the UP unless it is abosolutly necessary.....and there is NO NEED to jack the engine to do an UP....and NO NEED for an UP on a stock turbo'd 2.5 with no UP cat unless the stock pipe is leaking or borked....

 

unless your Turbo'd 2.5 has a pre cat like mine did

Here is my install:

http://www.scoobymods.com/forums/showthread.php?t=5157

I agree though, if mine didn't have a pre-cat I would not have messed with it. When I did my install I jacked up the motor a little because I didn't want to remove the turbo. I'm not sure it could have been done w/o doing that, at least not easily.

 

Thanks for the back Peaty... I am at a loss on how you guys got the flange past the block/frame without moving jacking the engine up slightly, but hey if you could do it more power to ya.

I actually got taken to the hole by a shop in So Cal before I knew much about my STI. They said that the up-pipe would help and I believed them... good news is that I paid 90 bucks for a PDE up pipe. Not too bad (they could have taken me for a high dollar item!). Hindsight 20-20, I would have left the stock up pipe.

 

is a aftermarket uppipe bigger than the stock wouldn't it be better to have a bigger one? what would you suggest my next couple mods be i have some spendindg money just looking for some advice?

 

I think in this case you want smaller for higher velocity to spin the turbo quicker.