de-cat

[nizmainiac]

just wondering if it's worth de-catting my e34 or not , as the cat rules on mot don't apply until 1992 and mine was made in 1989

[Alexlind123]

Sure, you will probably get more power especially at higher RPMs.

[hatched91]

i was wondering the same. i was thinking remove my cat, and replace my tri-flow muffler with a borla muffler, but leave the resonators and piping in from the tri-flow cat-back. i think w/o a cat it'll give it more air-flow and with the borla muffler, it'll give it a more throaty sound. whenever you hear that distinctive sound of a mustang cobra that is super loud and very throaty, it's borla. about 30 of them are around my area that i see and hear daily. but what about the computer? will it still run okay?

[BigKriss]

What does the computer have anthing to do with the cat. The o2 sensor is before the cat - you will have no problems.

i was wondering the same. i was thinking remove my cat, and replace my tri-flow muffler with a borla muffler, but leave the resonators and piping in from the tri-flow cat-back. i think w/o a cat it'll give it more air-flow and with the borla muffler, it'll give it a more throaty sound. whenever you hear that distinctive sound of a mustang cobra that is super loud and very throaty, it's borla. about 30 of them are around my area that i see and hear daily. but what about the computer? will it still run okay?

[nizmainiac]

i'd forgotten i'd asked this, good to know it can be done with no ill after effects

[bmw_ryder]

i've detached my cat from my e34 and putted an sport muffler,the sound is great,and with this modification i think i've obtained till 5hp.
the cat is an part that need to be changed in time,but few people know that.
mine was broken

[nizmainiac]

yeah i know . i've changed a fair few of them in my time

[hatched91]

yeah i didn't look under the vehicle before i asked, i know some have precat and aftercat or just after cat. i think i'l talk to a few muffler shops to get a price quote. i'd like to go with no cat and a borla muffler. that means b&b tri-flow muffler will be up for grabs soon.

[hatched91]

yeah got to looking and you're going to need two long pipes that are bent and what not, my guess around $100 at a shop. i want to go y pipe after the downtubes to a 2.5" pipe all the way back to a borla muffler. does anyone know if it's better to have the muffler at the end or have a tailipipe with a tip?

[hatched91]

okay, went and had the cat cut out. cost be about $60. one pipe was 3' long and the other was 3.5' long. i have a cat-back b&b tri-flow exhaust and it really sounds like garbage, but then again there are a couple of exhaust leaks. i have 2.25 piping back. i believe if i can sell the cat-back exhaust, i can have true dual exhaust run with two glass-back style borla mufflers. i believe that will give me a much throatier tone.