Thanks to the efforts of Roverite the following has been accomplished.
We have successfully tested the 'Longlife' chambered (and quiet), rear exhaust section and here is the result.
Firstly a bit of background. In the past, mainly in the 'classic car' scene, SS exhausts gave a corrosion free alternative to the short lived mild steel OE fitment, but many SS units suffered from increased noise, either actual exhaust noise, or a rather 'tinny' sounding exhaust, because of the poor quality stainless steel used in the construction. Longlife have developed SS exhausts over the years and by using superior materials and engineering, now have an exhaust to fit any car, which is covered by a lifetime (of the car), guarantee. There are 'franchised' outlets all over the UK and each exhaust is fabricated for each individual vehicle. The system, which is made up from various basic components, is also made to the specific requirements of the owner, so you can have straight tail pipes, curved tailpipes, noisy or quiet silencers, etc. It is also possible to have just one section fitted, eg., the rear section, but it is probably worth getting the complete system whilst it is in the workshop.
Rover 75 was actually designed to have a SS exhaust, and a few early cars off the line, were so fitted. They all have a basically SS catalytic converter, so this doesn't need changing if it is OK. Some diesel owners have the 'cat' removed, but whilst this is not tested on the MOT, the latest EU regulations say that all equipment present when new, must also be present for the MOT. The choice/risk, is up to the vehicle owner. Although some members say that removing the 'cat' makes no difference to the noise levels, I found that mine was noisier between 1200 and 2000 RPM, so I had it refitted; petrol versions must NOT have the 'cat' removed.
The Enthusiast decided to investigate the merits of getting a very quiet exhaust, commensurate with what was fitted by MGR; to this end we enlisted the help of Longlife, who are at the top of their game when it comes to SS exhausts. They are also very accommodating and fully back the quality of their work. MG ZT owners may not want a really quiet exhaust and many like a rorty exhaust note, but these owners can also be catered for. However the purpose of this 'trial' was to get the quietest exhaust possible, primarily for Rover 75 owners, and that is why Longlife offered up their new chambered rear box for evaluation. Longlife were very confident and asked for a V6 Auto for the test, because these are notoriously difficult to keep quiet.
With the help of the 'Community', we found a member who had a low mileage V6 Auto, still with the OE box and within a reasonable distance of their factory in Dorset. This car was fitted with the new rear box (keeping the front sections as OE), on June 26th and the owner was very pleased. He said it is "very, very quiet" and "is at least as quiet as the original unit"; this assessment was from a longish journey home, with speeds up to 60 MPH, plus a few miles of local town journeys. Jason from Longlife had already told me that he was very satisfied with the results and thought the customer was too; he was.
Costs can vary because of the fitting location, for example London labour rates will be higher than other parts of the UK, and special customer requested features can hike the price a bit, but Jason has quoted Â£399 for a full system, or Â£249 for just the rear section, which is not that much more than a new top quality MS unit. The prices will not vary between Saloon and Tourer, but the V8s will be a lot more and will need a one-off quote. One final thing; the new box has a single tailpipe outlet (approximately equal in area to the two outlet OE unit), but if you want two for appearance sake, then a 'Y' piece can be made up, although it is hidden behind the rear bumper on standard cars and therefore only visible from underneath.
There are some pictures below, but that is about all of the writing for now, except to say that you should check out 'Longlife's' website, which can give you a list of outlets and a good idea of the company's ethos.
Jason Freeman = firstname.lastname@example.org Tel:- 01308 422282.