Nope, but all the Cavalier / Calibra and Vectra boys seem to do these mods.
One of the chaps who worked at the Ellesmere Port V6 factory on all aspects of the V6 for the 9 years of production told me that he tried a Vectra B with a 3.0 conversion and lightened flywheel and it was the fastest accelerating V6 he'd been in, the only downside was that the engine braking when changing down was vastly reduced.
Oh and another good mod would be 3.0 cams (G I think).
All depends how much you want to spend. If it was me i'd probably keep it pretty much standard if it was a second car..... famous last words!!!
Then again...
Cavalier Turbo bodykit 
Cavalier / Calibra Turbo Alloys 
Leather seats 
Oh no, you've started me thinking!!!!
picked her up saturday. black cdx 2.5i 24v V6 L-reg, c25xe engine with red lid, full leather, full electrics, every option ticked, powerflow stainless system, interior immaculate, leather looks like its never been sat in apart from slight wear on drivers bolster, irmscher boot spoiler, koni adjustable shocks and eibach springs lowered 40mm, 17" 5 stud 5 spoke alloys, full vxsh, aircon, abs, tc, alarm, immobiliser, a shade over 100k on clock (nothing for these engines, especially for a 14 year old car), ONE OWNER FROM NEW(!), new fuel tank, new radiator, years MOT, new alternator, new windscreen, tyres look like brand new AND original CDX alloys with new tyres thrown in as well. cambelt doesnt need doin for a while. the list goes on. i am stoked. properly stoked. body is in great shape too.
she's only done 10k miles over the last three years and averaged 8k a year from new so under the bonnet seems to be in tip top condition as far as i can tell. i'm sure some snags will appear over the coming weeks but nothing that raises alarm bells.
going to apply a few mods and bits to play about with, but overall i'm dead chuffed. she flies too, and mrs ilovemyelite doesnt mind finding her lead foot either hehehe