Here's how to tell:
First, a reference photo of a 1050 header:
It's always a good idea to cary a spare...
Now a crop showing the outlet tube from the collector:
See the weld spot approx 1cm behind the collector outlet?
You will see another before the bend if you follow the tube back along that line.
There are two similar welds 180 degrees across the tube.
Those four welds suspend the precat tube in the center of the outlet tube via four ~5mm stainless steel pins. If you don't have these welds, you don't have a precat ('05/'06 anyway, newer bikes may locate a larger precat a bit farther downstream).
The precat tube is about 1cm smaller O.D. than the exit tube I.D. You can guage the precat length from the weld locations.
If one were to theoretically drill out these four pins, one may then discover that the floating precat tube is too long and rigid to exit the outlet tube bend. One may then have to grind down the outlet to collector weld and remove the outlet tube to free the precat. One would then likely have to find a stainless capable welder for reassembly and then hope the alignment is close enough for reassembly.
Once all of this was done, one may discover that:
A) The precat flows freely and little (more likely no) power is gained.
B) Most of the seat heating is due to the large efficient cat in the muffler.
C) No significant difference in sound (see A)
D) One may not care for the stench he is subjecting his fellow man to.
Due to A through D one may declare the experiment a failure and replumb to
OEM configuration.
This is all theoretical of course and I am running full plumbing.
The adjustment that I *have* found worthwhile is progressively increasing ignition timing below 10% throttle. Triumph pulls timing in that area to provide a benign throttle response. As a consequence, efficiency suffers in town and the cats runs hot because (drum roll please) that's where a significant portion of the fuel is being burned.