I don't even want to open the hood on a car anymore. There's nothing under there for me.
On newer cars, I would agree. You'd spend 3-4 hours digging out hoses, covers, spagetti wiring etc before you could actually *see* the engine.
Thats why I like my 93 crewcab, a lot. I can actually work on it. Well, everything but brakes and wheel bearings. I don't have a lift here, so I have nothing to lift the 7000lb truck.
You ran an engine... for 2 hours at 2500 rpm... with no exhaust??
Wouldn't that... I dunno... burn up your valves or something?
Naaaah, doesn't hurt the valves at all... in fact, the opposite is true - too much back pressure can cause carbon deposits on the exhaust valve as well as significantly increase valve and stem temperatures and reduce overall engine efficiency.
Also, I have the engine on a homemade run stand, so there isn't a load at all. On the back of the engine is a flywheel and a starter, covered by an old bellhousing, and thats it. Its like revving it in neutral, so there is no load to speak of. Lack of load made it difficult at first to keep the speed constant... but thats another story.
When things get further down the assembly process, and I make better turbocharger manifolds, the final exhaust system will be:
manifold(s) --> turbo(s) --> "Y" pipe --> straight 5" pipe --> atmosphere
I'm going to be using the turbos, as mufflers. No cats, nothing fancy, just careful EFI tuning for emissions compliance.