So I went ahead and bought this. It looks much weaker than the stock setup though?!? Here's a few pics.

Extreme duty:


Stock:

 

Great choice. The extreme duty timing set is the best one you can buy if you are planning on staying with the cam driven water pump. If you were lets say entertaining the idea of an electric pump then you could upgrade to a true double roller which in this case is stronger than the extreme duty that you have. But to be totally honest, you probably would never have a problem either way. The stock set is pretty much as crappy as any OEM timing chain. They stretch and are very weak. This new set will ensure accurate and reliable timing for years to come. ENJOY!

 

A simple HOTcam caused a replacement OEM timing set to get pretty loose on my car within about 10k miles. From what I've read on here from some of the most knowledgeable people on this board, the LT4 extreme duty timing set is strong enough to stand up to more than most people will ever throw at it.

 

Go back and look at your own pictures... the LT4 XD chain is a true roller.... the stocker is not.

I've seen the LT4 XD set support 1,125HP in an LT1 running huge spring pressures on a solid roller cam, and turning to 8,000rpm redline. I have the LT4 XD on my lowly 800HP setup, but the solid roller cam is only running a 7,200rpm redline though. I did remove some of the bulk in the cam sprocket, since that bulk was put there by GM to solve some problems with the LT4 cam twist.

http://members.aol.com/Fredrick518/Photos/newfront.jpg

 

Just finished installing it. It's amazing how little slack there was compared the stocker. Now if only my dist gear would get back I could get the rest of the engine assembled.