Tippman Custom98/A5 with flatline and with 32 Degree Nyte Stick 14"
Pretty low cost, good improvement in consistency
Had to make the link rod hole slightly larger
I've had great results with this bolt. It's not going to give you instant one inch groupings, but it does improve the consitency of your shots. Other reviews I've seen put it at no improvement from the stock bolt, but I disagree- I have seen improvements, though not as dramatic as other reviews on this site.
I did notice that as I was installing it that the rod that links the front bolt with the rear bolt fit into the hole of the bolt too tightly. I used a drill bit to widen the hole just slightly and it then fit like the stock bolt. (Don't make the hole deeper though.... you might go through to the inside of the bolt.)
Installation is the same as the stock bolt. A Good addition to this bolt would be an aluminum replacement of the power tube. (see other reviews of these power tubes.)
Wait for one on sale (I got mine for $15) and you won't be sorry. I have seen them for $30 and I think you could get more of an improvement in accuracy by spending $30 on an improved barrel or regulator. But still, this did improve my shots.
You don't have to drill out the hole. It just fits really snuggly. I just got one and installed it with no drilling at all. I just worked the bolt rod back and forth while applying some pressure and it fit in just fine. I HIGHLY advise against drilling to adjust the fit. It WILL go together trust me.