Hello !
I want to share my experience about replacing exhaust system. I've done a service on my Lex G300 2005 3.0 V6 and they found an exhaust pipe is split in place where it joints a middle muffler. They quoted a job for nearly 1200£.. because they sell this part altogether with two rear cat's. As you guess I didn't let them touch it even, especially Lexus Centre in Birmingham - their service is the worst I've ever experienced - but alright it's a different subject.
I decided to go into a stainless steel Exhaust system. I searched some info on the internet and found that many people recommend John Ashley Exhausts in Walsall. I called them and arranged a job.
I spoke to a man at their place, decided to replace a whole cat-back system and chose what tail pipe I want and how I want it to sound. I went into the most quiet system they can do, but with a hint of nice roar when I strongly accelerate.
After around 6 hours they finished the job. It looks amazing, but I can see they didn't install a middle muffler, so what's going on? John (an owner) said that according to their experience two rear boxes should be enough especially for automatic car. I do not really know what influence an auto gearbox can have on exhaust but ok. When I started an engine I said.. WOW man, it sounds gorgeous. It was late, so I said I will check it on my way back to home and let him know what I think the next day. It sounded great on idle but on the motorway it was a disaster.. it was TOO LOUD, definitely TOO LOUD. So I went back to them next week. They put a middle muffler on as well and didn't charge for job, just for a box.
Now it is AMAZING sound especially over 3'000 rpms. It is close to perfection, could be slightly quieter in range from 1800-2600 rpms but it is NOT TOO LOUD now. It is acceptable, but when I hear this roar over 3000 rpm's IT IS WORTH to have a little droning below 2600 rpm's :)
After a month I had put some sound deadening mats and liners in the boot and now is alright at lower rpm's.
To sum up, the OEM Exhaust would cost 1200£ and would give this amazing silence inside the car which is so great, but honestly V6 enignes shouldn't be so restrained. Now when I accelerate everyone around knows that it's not a common saloon, it's a real BEAST :)
Now I have a really great genuine V6 sound and amazing looking of stainless steel exhaust for as litte as 470£.