If a MHG is installed propely it will last you the life of the motor. However, to properly install a MHG, you can't just pull the haed, slap one in and go. In order to install a MHG, you must pull the head, and get it machined, then machine the block as well. If your shop doesn't have a Block Lapping Tool, this means either finding another way, or pulling the whole motor. So, to sum up, you'll need:
1) ARP Hardware (Head Studs or Bolts, OEM Bolts WILL NOT cut it)
2) Proper Sized MHG
3) Machined Head
4) Machined Block
5) Proper torque (I used 85ft-lbs instead of the 55 that Toyota says), and then checking the torque spec a month or so after it's been running.
Failure to do any of these things (except maybe check on it) can easily result in a blown head gasket. I can't count the number of blown MHG's I've seen because the owner DIDN'T get the block machined.
As for CT26 upgrades I assume you either mean the 60-1 upgrade, or the 57trim upgrade. From what I've seen of these, they do make good power and people seem to like them. However, at the same time, it IS cramming a larger wheel into a housing which wasn't designed for it. So on top of that, the shaft isn't designed for that increased load. With these additional forces, the shaft is more prone to breakage, and has a little harder wear on it.
Besides that fact, I'm not personally impressed. A guy in my town, required a 60-1 upgrade, 8 more PSI than I was running, an intercooler setup, a complete fuel system, and a lexus AFM JUST to get 85hp more than my dyno. Those numbers just didn't impress me, so I decided that wasn't the way to go for me. I personally chose to go to a full out new turbo (Garett T04). But, like I said, people seem to like 'em and they're a pretty simple (-ish) upgrade for easy power. Just make sure the rest of your system can take the added forces/boost.
