2ndary Cat/Res delete.... Harmful?

[Mark Ducati]

Hi Fellas,

I was all set to have my local muffler guy install some "test pipes" for me for this delete... all I wanted was some more sound out of my ride...


I spoke with a Dinan installer (Ron Trochelmann of Performing Imports in Atlanta)... told him I was going to have some test pipes installed, but I called him to ask about tuning the computer... he's got stock tunes to match whatever mods I do to the car, but each tune is like $1000 bucks! Ouch!

The Dinan exhaust is $3000 bucks... I guess he's leasing his M6 as he's turning it in in a few weeks for a new 2011 740i... he offered to sell me his old exhaust for $2000 bucks.

He was telling me that installing test pipes could harm my car and that especially installing an H Pipe or X Pipe would equalize the pressure in which the system was not designed for...

I'm thinking, this all after the primary cat sensors... could and engine that blows exhaust easier somehow tell on the front end? I don't understand how this could harm the engine?

What I question is his eagerness to perhaps sell me his used exhaust... sure its a good deal, but I dont have a spare $2000 right now when I can do the 2ndcat/res delete for a couple hundred dollars.

His last comment was why would you go cheap on a $100,000 car? Yeah, I get his logic... but my pockets aren't as deep as his apparently.... Don't get me wrong, I'm not trying to call Ron out, he seemed like a very nice guy and a very knowledgeable one at that too...

So what do the rest of you think about the 2ndary cat/res delete... harmful or not?

[tmiked]

There is no harm whatsoever.
Just some more HP and a little louder.

You received some really silly BS advice.

[waleed_wales]

thats total bs

i did this mod and my car is way better now (performance and sound wise)

[Mark Ducati]

Another thing Ron said, was to make sure NO welding is done on the car with the mufflers hanging down... he said that it could fry some of the computers...

I wonder if I should disconnect the negative terminal of the battery first?

[tmiked]

Originally Posted by Mark Ducati

Another thing Ron said, was to make sure NO welding is done on the car with the mufflers hanging down... he said that it could fry some of the computers...

I wonder if I should disconnect the negative terminal of the battery first?

Cant hurt to disconnect. But, mostly its more BS.
Be sure to ground the welder solidly on the exhaust pipe.

Sounds like he is trying to make you afraid to do any work on the car yourself.

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[waleed_wales]

Originally Posted by tmiked

Cant hurt to disconnect. But, mostly its more BS.
Be sure to ground the welder solidly on the exhaust pipe.

Sounds like he is trying to make you afraid to do any work on the car yourself.

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That's very obvious, don't listen to him and do it urself and save couple of hundreds on other mods

[KSA ///M5]

I removed my secondary cats and gaind 12.66 whp, I kept my stock resonators though. My Catless Stock Exhaust Dyno Results 477 WHP

[steven0720]

how much louder catless with stock exhaust ?

[iroquis_pliskin]

removing the 2ndary cats should be fine to our beast.
I replace my 2ndary cats w/ straight pipe, thus gives louder sound on my exhaust

[Hasan Shaikh]

The secondary cats and resonators are both different.

Removing the resonators should not be a problem. Removing the secondary cats may result in a loss of back pressure and may cause a loss of torque.