So, I have been planning a compete hose replacement on my SV8 since over the last year three have leaked and just the other week, one blew (small elbow from block to thermostat housing) and I had to get the car flat bedded back. Fortunately, I had all the hoses (except for the upper rad hose, but it's on order) in a box in the garage, ready to go since I knew the day was coming! So, just the other day, the hose from the EGR to the thermostat assembly decided to go, well, might as well do them all since I didn't want to be driving around worrying about a hose going. Here is the pile I ended up with (also some knock sensors in there as I was getting an intermittent code for them):



Also, this is what the original valley hose looked like after all this time, just starting to bulge:



I don't know how these hoses fail so early on some cars. Our STR was just bulging when I did it too. I wonder if the cars being in a cold climate helps prevent heat damage?


Now, this is not my first rodeo! I have done the job on our STR a few years ago, twice (oops, forgot a bolt, back in I go!) so I knew what I was doing. Total time was about 7 hours over two days (no rush, taking it easy). Overall, this was easy compared to our STR. That car only had about 160,000 kms when I did it and it was a disaster. The EGR bolts rounded, everything was FULL of gunk when it came off, and a bunch of other little things. So going into this I was expecting the worst, however, that was not the case. Every single nut and bolt (including the EGR to manifold and throttle body) came off as easy as pie. The second surprise was how clean everything was. There was barely a light coating on all the intake parts. The EGR valve was so clean it looked like i was new and almost no carbon/gunk on the throttle plate. You'd never guess the car has almost 300,000 kms on it.

Intake parts:





Now, not perfect, but compared to other cars I have got into at higher miles, this looks new! (Others may have other opinions if this isn't considered clean!). Usually I have to scrape and clean a thick layer of gunk off everything (MAP sensor was almost buried on the STR). Now this car came with a FSH, so I know all the hoses and stuff are original, so this hasn't been cleaned up or any hoses replaced before. This is making me feel that this car will easily go another 300,000kms! Still getting about 30-33 mpg on the highway.

I did discover I need to rebuild the supercharger (not terrible, but needs it) so I'll be doing that and putting a smaller pulley on when I get a chance over the next while. But, what's another supercharger removal. Buy now I'm an expert!

 

That's a very honourable mileage and shows a good durability of your components and hoses! (my SV8 suffered a breakdown of the valley hose at only 60.000 km, but indeed it may have suffered from very hot environments during its first life in the Emirates...)
Congrats for the job also, not an easy task, I couldn't have done it myself

 

In case it helps, a recent (UK) Car Mechanics has articles about superchargers with a detailed one about refurbishing the M112.