Another Exhaust Problem (me thinks?).

[AC]

Hi Folks,

Being my first post I must start by saying thanks to one and all (especially site creators/moderators) for a great information resource.

I have just recently changed my standard cat back silencer for a Magnex and replaced standard filter with a Blitz panel.  Since then had a number of issue's never previous experienced (started with CEL, reset ecu and it cleared only to come back 3 days later, so cleaned MAF and reset ecu Friday and so far stayed off).  However, yesterday whilst out driving and having wound engine up to 7000 rpm I susbsequently developed what I can only explain as a 'blowing' noise presumably from the exhaust, which gets more audible with engine speed.  This morning I got under the car thinking it was the joint where the cat pipe out flange and silencer pipe in flange bolt together, having recently been disturbed with the change.  I can't say it is this, if anything the noise is eminating more from around the manifold.  I removed the two oxygen sensors and the pre-cats look fine.  Has anyone had a similar problem?  My thinking now is that one of the following may have gone;

Manifold gasket, or
Manifold itself, or
The joint or pipework either side, manifold to cat (I can see a couple of what look like flexi's below pre-cats, do these ever blow?), or
Cat, including that pipe stretch.

Problem is nothing as yet is apparent, no holes, no gas visible on cold start (except from tail pipes) just the ill sounding noise.

[loadswine]

The magnex should be a fairly friendly piece of kit in itself. There is a circular cone type gasket on the joint between the backbox and cat section, that may be the source of blowing if it has been left out or damaged. Its possible that something else has been damaged, but it all depends on the fitting of the new rear box. It should fit okay if its a Magnex, but if  the system has been bashed around or mistreated, then I guess collateral damage could be in evidence elsewhere.
Check the third O2 sensor beyond the cat for damage too.

[AC]

The exhaust was brand new, bought just two weeks ago (without warranty though with Magnex going pop) and fitted by the local Toyota dealer as the car was being serviced and MOT'd last Saturday.  I inspected it prior to fitting and it was A OK outwardly.  Today I have had a good a look, feel and listen around the joint with the cat section and I don't think that's the problem though admittedly it is a little tight so can't see between the two flanges even with an inspection lamp.  It sounds a lot more like the manifold area.  I did wonder whether it could even be engine related rather than exhaust?  At cold start it does sound a little 'cammy' since it came back from service/mot/exhaust, but I thought nothing more of it than the exhaust change.  I think its back to Mr T for diagnosis.

[loadswine]

Taking it back to the place that fitted it is a sensible choice. If they sort it for you, you can then enjoy your new exhaust.  s:) s:)