Both cams work well.
Having installed about 5-6 of each cam. The lope on the S1X is actually a little more noticable than the XP on stock idle speed. Really though it all depends on where you stand (behind the car you hear the cam the best) both cams are pretty mild and don't stand out much. Add a 100 rpm to the idle and you'll barely be able to tell there'* a cam in the car.
As for adders and power. I had quite a list of stuff and estimate the car topped out at around 450chp. It was an awesome amount of power.
Stock bottom end
S3 PRJ Heads (front head drilled/tapped for L26 dogbone bracket)
1.8 HS rockers/comp cam reusable bolts
Intense 3/8" pushrods (stock length)
ARP Head Studs
Ported LIM (gasket matched and ported every way possible, with post rotor temp sensor)
S3 WBS IC core
Meziere electric water pump
Modded 97 TA mount bracket
00+ alternator (with sense wire added), tensioner bracket, ps relocation bracket, oil pan, pickup tube and filter adapter
Oil pressure increase kit
8 rib SC belt path
Ported Gen V with snout turned down (could run a 2.5" pulley)
2.9" pulley for street
4" FWI with K&N filter
L32 MAP sensor
LQ4 MAF sensor
Customized 99 L36 wiring harness to work in 97 L67
Meziere 20gpm pump for IC
Sirroco radiator as FMHE
Custom "Foghorn" IC reservoir tank
Custom front (solidified) motor mount
Many fully build race transmissions with 3.29'* and 7/8'* chains. (weak link of drivetrain under my right foot
LC-1 Wideband O2 sensor
3" cutout before catalytic converter
Full 3" exhaust to bend before fuel tank (after that it was stock)
Drag bags (keeps the front end down so you spin much less)
PRJ fuel rails
255lph TRE Performance fuel pump
26 x 10 x 15 MT ET Drag slicks
Oversized El Dorado radiator
ABS defeat wired to button in cabin (pcm can't see wheel speed = no torque management)
PRJ spark plug wires
There'* many more interior mods and upgrades like buttons, gauges, subframe bushings, sway bushings, sway endlinks etc etc etc that I'm not listing as this is aimed at putting power to the ground.
Now when you ask, which cam is better XP or S1X, ehhhh by itself they are both about the same. You can with research do about the same as the list above with either of the two.
And yes.. all cars feel slow in comparison to when I had the above setup in my Bonneville.