Hello and Welcome to justanswer..
My name is XXXXX XXXXX Im happy to help you with this.
If you have a reasonable mechanical knowledge and a reasonable array of mechs tools, I see no reason at all why you couldn't do that yourself ...
It really is only mechanical work - nothing technical involved - just a case of taking the old cat apart / out of the old exhaust system - and replacing with the new. Some models / versions of these have the o2 / lambda sensor screwed into the cat itself - others have them in the exhaust piping before and after the cat.. If yours is actually in the cat- you will have to swap it over to the new one thats all.
The biggest problem by far with anything to do with exhaust / cat work - is the fact that the old nuts / bolts / fixings get seized over the years with the heat -and being exposed to the elements. You often have to cut the old nuts / bolts off - or, use a blow lamp to heat them up to remove them... or - you can just use your tools to snap them off.. Either way its best to have new fittings nuts/ bolts to fit the new one back - its makes for a better job / fixing -and makes life so much easier than re fitting old rusty nuts / bolts..so buy them at the same time.
As to where to get a new unit - I strongly suggest shop around. If you are happy to buy over the net - and there is nothing wrong with that - shop around and get the best prices and go with that... you can save a lot of money that way.
Im afraid I don't have US or French prices - but I will give you a link to a UK site / company where you can check - you can get them sent to wherever you are-- but again - check out prices on the net / via google etc to get the best .... but the link to the one I have in mind is HERE
for you.Let me know if you need anything more on this at all -
You need now to click on the OK rating to Excellent ratings service for me now, Thank you for that... and you can get back to me anytime if you need / wish..
Best Rgds, MIKE. Please note, you are rating the content of my "answer" - my help to you - not the "system" which can experience delays etc which are not under my personal control -or delays caused by "time -off" which we all have on occasion - Thank you.