is it safe to run without a cat or muffler?
 

hey i have a question is it safe to run my car (05 sti) without a cat or muffler?

No. You will hit boost cut.

besides boost loss
 

besides losing boost is it safe on my car (05 sti) to run without cat and muffler

One thread would suffice, don't you think?

Welcome to the board, by the way.

Yeah welcome. oh and about the catless thing. Why do you want to be without muffler too?

If you go catless, you should look into getting engine management like the AccessPort to help control the potential for boost cut.

Boost cut is not a "loss of boost", it's "so much boost, the engine is trying to save itself by cutting the fuel".

Unless you've ported the wastegate on the turbo to allow the stock map to properly regulate the boost, you may have potentially engine-destroying problems with catless exhausts.

Welcome!

What exactly are you trying to get away with?

This digram may help you describe what you're hoping to accomplish.

http://seccs.org/forums/attachment.p...9&d=1162159734

I understand the need to keep the diagram succinct, but the fact that the intake and exhaust are pointing the same direction in that pic always gets a chuckle out of me. :D

Jeremy I see you eyeballing that diagram

How did you know?

But I could have guessed anyway. :lol:

At any rate, wouldn't running sans-catback be acceptable? Silly, sure, but not dangerous?

Probably, but the lack of back pressure could theoretically cause over-boost since it's an STi.

Except for the ridiculous amount of noise being generated.

I would think the same. It would be LOUD but not dangerous.

Yeah, STis have a tendency to overboost in stock setup sans cat (or catback).

It won't harm your vehicle, in theory, because you'll hit boost cut and have the fun of driving in limp mode for a while.