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150 Posts
Discussion Starter #1
High Flow cats in Stock class?

I was wondering if you were aloud to replace the cat on stock class cars with something besides the stock one.
 

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Discussion Starter #3
I have
K&N air filter,
2 1/2 cat back exsaust with a AreoSpeed Muffler (striaght through)

What else can i do in stock class to help the power of my car?
 

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Change the spark plugs.

That's about it. Unless its an item that will normally wear out (and wouldn't normally improve performance) assume that you can't change it. If its internal to the engine, assume that its got to be OEM parts. If its emissions related, its got to be OEM.

I almost forgot... you can do anything the Factory Service Manual allows. If the FSM allows an overbore, you can do that. You can balance the engine using factory parts that are all within tolerances specified in the FSM, etc. But now we're talking about large amounts of money for 5 or 10hp.

Andrew.
 

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Silver '99 Impreza 2.5 RS
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118 Posts
You could remove your muffler entirely.

You could replace your stock wheels, with the same dimension wheels (16x7) except in an ultralight (and ultra-expensive) variety. That'd help your acceleration by eliminating rotating weight, but that's getting pretty esoteric.

Basically, you're pretty close to the limit of what you can do (power wise) legally and remain in Stock class. That's why they call it stock, after all. Pretty much the only things you can change are items that normally wear out.

Spend your money on some good shocks and some R-compound tires (if you haven't already) those are the two biggest things you can do to the car in Stock to go faster.

Sean
www.subrew.com
 

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Yeah, yeah, yeah... I still need to just do the regular cat-back exhaust. Its on my winter "to do" list. The stock setup is starting to rust.

The other big item is driver mods. My car has gotten a lot faster without modding anything other than the driver. And its not just my Subaru that is faster, either. Everything I drive is faster!
 

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Discussion Starter #7
I defently know that the driver is most of the placement. but i like power more for daily driving.

I throphyed last auto-x and my time was good for 2 places faster if i wouldn't have hit the cone. but it was raining and i couldn't see out the window well

Erik S.
 
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