Exhaust question

[m3nace]

Hi guys,

I have recently decatted my E46 M3 and had a straight pipe fitted. I like the sound but I feel a drop in the mid range torque:bawling:. She doesn't pull well through the gears any more. Should I just fit in two silencers? I beleive the torque drop is due to exhaust back pressure or something like that? Any info would be appreciated.:thumbsup:

 

[FJD]

This is one of the things I fear most,at my last service I was warned that my cat is needing replacement,and due to the huge cost factor (R30 000 or somewhere in that region) There is no way that I will be fitting a new cat,but after this post I'm a bit concerned about removing it a fitting a freeflow.

 

[///M335]

you guys are not doing it the proper way!

 

[FJD]

you guys are not doing it the proper way!

What is the propery way then ?

 

[m3nace]

yes do explain

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This is one of the things I fear most,at my last service I was warned that my cat is needing replacement,and due to the huge cost factor (R30 000 or somewhere in that region) There is no way that I will be fitting a new cat,but after this post I'm a bit concerned about removing it a fitting a freeflow.

Dude, bear in mind that the drop in mid range torque is, I would say, 5%.
My boet drove the car on the weekend and he says that it feels the same - just with a better tone. It's just that since I drive the car everyday, I feel the difference and want to get the torque rectified. Personally, I would rather spend R1k on a decat than replace the thing at R30k.

 

[FJD]

yes do explain

---

This is one of the things I fear most,at my last service I was warned that my cat is needing replacement,and due to the huge cost factor (R30 000 or somewhere in that region) There is no way that I will be fitting a new cat,but after this post I'm a bit concerned about removing it a fitting a freeflow.

Dude, bear in mind that the drop in mid range torque is, I would say, 5%.
My boet drove the car on the weekend and he says that it feels the same - just with a better tone. It's just that since I drive the car everyday, I feel the difference and want to get the torque rectified. Personally, I would rather spend R1k on a decat than replace the thing at R30k.

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Thats about 5% more than I would like to loose.
I won't even consider getting a new cat,they are waaayyy to expensive.

 

[///M335]

it takes close on to a day to remove the cats and keep your original exhaust in place,
without losing power and without it sounding like a 30s cortina. LOL

 

[FJD]

it takes close on to a day to remove the cats and keep your original exhaust in place,
without losing power and without it sounding like a 30s cortina. LOL

lol

 

[444YYY]

You need to tune it now....

 

[FJD]

You need to tune it now....

Ahhh...so the key is to tune it so you don't loose the power after removing the cat ?

 

[444YYY]

Obviously the engine breathes differently now, so you need to optimise the fueling and ignition to match this new breathing characteristics.
Personally, don't expect a mamoth increase in power though. Be realistic....