OK, let me give an insight into titanium welding.
Titanium, among all metal is the most unfriendly, most difficult to weld. Its a very special grade of metal whereby its 30% lighter than steel and almost as strong as steel given the exact same dimension. Its also very very sensitive to air during welding. This means that special care is needed when one does titanium welding.
First and foremost, titanium needs to be cleaned properly prior to welding. And you need to remove air/oxygen from the area you wanna weld. Assuming you wanna weld a pipe, you have to flush/purge the pipe with argon gas for about 10 seconds or so. Again, that depends on the diameter of the pipe. The bigger the diameter, the longer you need to purge. After purging, you can start welding and after welding, you need to cool the welded zone also with argon gas so that oxygen does not get into the molten titanium zone before it cools completely. This is what you call trailing and you use argon as a trailing gas. You don't need a vacuum environment to weld titanium but rather it has to be relatively free from air so that it won't destroy the weld and have porosity in the weldzone.
Basically thats about it but what i'm trying to say here is titanium is not an easy metal to weld and whatever you read in magazine about titanium pipe are just marketing gimmicks. First and foremost, its not cheap at all. For a complete exhaust from extractor to muffler tip, i'm estimating that the cost alone for pipes and welding is probably 30K. Its that expensive!! And i've not even incluided in bending, whereby you need a good pipe bender to do the job as it'll crack when improperly bended. And if someone gives you bullshit that only the muffler is titanium, thats plain bullshit even if the best exhaust shop says so. Its simply because titanium DOES NOT bond with any type of stainless steel or carbon steel. Its a very unfriendly metal which won't bond even with the highest stainless steel grade. So you find that a true titanium exhaust will come from extractor right to the muffler tip. Boy, that is not cheap at all! Unless your exhaust shop owner tell you he uses glue to stick carbon steel piping on titanium muffler.
The only reason why people use the term titanium piping/muffler is that the blueish and goldish finishing on a so called "titanium muffler tip" actually looks very similar to a weldzone of a titanium material. The quality of a titanium weld actually is determined visually by the color it produces when its properly cooled. A good weld is normally blueish. That is why some exhaust manufacturers claim its titanium muffler tip when in actual, it only looks like titanium finishing.
So guys, i'm not saying "titanium mufflers" are lousy and bad. What i'm trying to tell you guys is to not succumb to marketing gimmicks. At the end of the day, the muffler may be the best muffler around but just becareful with what they claim and how they earn an extra couple of hundred bucks just because its 'titanium muffler'.