TDI Straight Through Exhaust (Gutted Cat + Backbox)

[d.mccarthy16]

Hi,

I'll be doing a de-cat on my 110 toledo in the coming weeks. I'm tempted to go full straight through to get the most performance out of the exhaust system, however, I don't want the 'boo' noise on lift off from the vanes closing in the turbo. Would just gutting some of the backbox and the cat still improve flow still give an increased performance with no 'boo' noise or is there any other way to do it on the cheap or is a milltek or the likes the only way to go? I would have imagined that if the sound had somewhere to resonate the energy would be taken out of it making it less audible. It seems the 2.5" pipe setups from the turbo back are the worse offenders. If it can't be done I'll just leave the standard exhaust on.

Thanks in advance,
Danny.

 

[dgjdrummer]

If you decat with normal backbox then it doesn't make that noise as loudly, otherwise a resonated turbo back may help reduce the sound but give a performance increase.

 

[GTJEDI]

Whatever you do dont get rid of the cat and backbox,I have just had to put my cat back on because it was far too loud and under boost the exhaust was drawing a bit of oil through the turbo seals.

The car wasnt driving as good either,I put the cat back in and left the straight pipe in instead of the backbox and its far better.

AL

 

[James_R]

I've always done straight throughs on my diesels but with the bora I'll be binning the cat and keeping the back box, lots of restriction in the cat.