That Sykes Pickavant kit doesn't seem to include the offset ring spanner required to properly adjust the belt tension on the revised idler adjuster, used model year '97 on. The original GM special tool is Kent Moore J42069-40?. A standard spanner, even a deep offset type, likely won't fit into the recess in the roller making it very difficult to hold the adjuster hex in the correct position whilst you tighten the TX locking bolt. Absent the correct spanner you'll find that the timing marks go out of line when you rotate the crank through 360 & 720 degrees. The special tool makes it way easier and quicker to get the belt tension correct first time such that the marks are consistently aligned as the crank is rotated.
The later Sealey VSE130 kits include the spanner. I think very early versions might not. Likewise the Laser and SP kits have no spanner. The Sealey spanner is VS1301 and is available separately to the kit and seems more readily available than the KM. So factor the cost of the spanner into your purchase.
Incidentally I've never had a problem with the Laser kit.