Aftermarket Exhaust Advice

It won't suprise anyone to know that Bert feels a little sluggish compare to our 1275 Siewalk, so it's time for a little power upgrade. Bert's 998 engine (a mid 70's Mini unit) runs well generally and the gearbox is good so I'm not going to rip it out and fit a 1275, bsides I like the 998 unit, so it's stage 1 kit time. My question here is regarding the exhaust; Obviously the stage 1 kits for sale ate Minispares & Minisport are for the Mini, which is a shorter car. What have those members with an aftermarket exhaust done about this? Is a standard length exhaust long enough that it doesn't get lost under the car? Is there a need to get the tail piece lengthened? Anyone sell an off the shelf unit if it does need to be longer.

Also whilst I'm asking questions regarding the stage 1 kit I have one more. Minisport is where I would have the car set up on a rolling road, and is about 50 miles up the motorway from home. Is it safe to fit the kit then travel 50 miles up the motorway without having it set up properly? Should I leave elements of the kit off to do the journey to MS? If so which elements?

Cheers folks

The Mini exhaust follows the same pattern as the Elf/Hornet one. Only the Elf/Hornet is longer rearwards of the rear subframe.
On the Mini exhaust which comes with the stage 1 kit (RC40 or similar) you could fit an extension piece for an Estate/Van to lengthen the exhaust: http://www.minispares.com/Product.aspx?ty=pb&pid=42840&title=

This is a stainless one with rolled edge, so looks nice at the same time

I would fit the kit incl. needle and check if the engine runs and drives fine, maybe adjust the mixture (a bit richer ? check the spark plug colour after a short drive with warm engine) and idle rpm and drive to the rolling road, without pushing the engine to the limits.