New exhaust system

Tuesday June 12th...
Yesterday I swapped my "old" BSM 4-2-1 system for a Laser ProfRace system.
I was actually planning to swap my steel system for a stainless system and thought I had found one in the form of a Laser ProfRace system. I even called the factory to make sure the complete system was fabricated in stainless steel (or "INOX" as Laser calls it).
But upon opening the box we discovered the headers are actually chromed steel!
So again I called the Laser engineering department for an explanation. It was explained to me that they don't do old systems in stainless steel for "economical reasons".
Though I felt misleaded I still decided to bolt the system onto my bike as I sold the BSM system a while ago and didn't want my bike to stay immobilised for another few weeks.
But I was pleasantly surprised when I had fitted the system and rolled it out of the garage to see how it looked from a distance.
I am very pleased with the result... the system runs much tighter below the engine (no huge gap between collector and oil sump), it also is very neatly tucked in below the footrest hangers and is angled more upward so I had to shorten the exhaust hanger.
The muffler is also a lot shorter so it stays well away from the rear. I thought the BSM looked good on my bike but now that I've got the Laser... well, judge for yourself...!

btw. both BSM and Laser systems are made in Holland.

Shown below is the old BSM Vampire 4-2-1...

...and this is the new Laser ProfRace 4-2-1

Update, July 22nd.
I took the bike to work, but soon discovered the bike wouldn't run properly at all. Bral suggested trying what it'd do with the choke open which I tried on the way back home and indeed it ran a lot better so it needed a bit more fuel.
That night I mailed OldKawMan for some advice and this was his answer...

"just looking at the laser I can see it would have a huge reduction in backpressure compaired to the BSM due to the collector location and much shorter, and much larger diameter exit pipe after the collector.
The BSM did not look like a true performance pipe, it was very long after the collector, flow resistance is directly proportional to the length of the pipe after the collector.
It is also proportional to 1/r where r is the pipe radius.
The primary pipe length before the collector will also change you low and mid range torque curve, there is a big difference in those pipes.
The BSM looks as it is designed for low-mid range.
You will need a larger main, throw a 140 or 145 in there and see what
happens."

I tried a 142 main jet, better at large throttle openings but still ran bad at small throttle openings.
A few days later I took the bike to Ruud who had it dynoed.
You can see the result below, 5hp up from the BSM which totals 140hp.
Strangely they went back to a 132.5 main jet.
On the road I noticed that it doesn't respond as well in the lower rev range as the BSM, which shows OldKawMan was spot on with his diagnosis, but when the bike starts climbing trough the rev range you can really feel the increased power... I don't notice any flatspot between 4-5000rpm anymore and it just surges forward with the wind pressure building up faster than ever! I wouldn't have thought that 5hp would make such a noticable difference.