Lets all remember engine displacement.
The MR2 and Miata have a few good things going for them, however, engine size isnt one of them. I am a firm believer in engine displacement being a good thing, especially when you have a nicely designed set of 4 valve heads to go with it.
A 1.6/1.8 miata will dyno 98-115 horsepower at the wheels depending on year. The MR2 spyder's 1.8 puts out 125 at the wheels on a good day stock. I wont compare the other MR2's just for sake of simplicity. For these engines to put out real power (to compete with the big dogs), you have to push 7-12 psi. The Miata with a BRP air-to-air intercooler and approx 9 psi pushes about 225 whp, the MR2 needs a bit less due to higher compression but is also more fragile.
If a 2.5 boxster puts out 150 at the wheels (just pulling this figure out of the air), you would need a 50% increase to match them in power alone. This could be done with about 4 or 5 psi and a liquid-to-air intercooler and a very small turbo which would have almost no boost lag. Due to its un-boosted size, even a 2.5 Boxster would have tons more torque so the difference in weight would be insignificant. Add in the fact that most of you are running rubber that you couldnt fit in a Miata's driver seat.
So yes, in a word I wouldnt push 10 psi with a rough tune at a Boxster. It's too much liability unless your sponsored and get free motors in the mail. However, at 4 psi I believe it would actually live much longer than being strung out at redline to eek all the power out of it. Start playing with hot cams, computer tuning, and increased redlines and the wear really beings. The real factor is keeping oil clean, pressurized, and cool but you have to do this with even a NA engine.
Our Project Focus SVT with 5 psi of boost on a MP62 blower (no intercooler and 10.2:1 compression) puts out more power and torque at 5,500 rpm than at 7,200 stock. The strange thing that even at 3,000 rpm it has more spunk than it ever did, so we tend to beat on it less just driving around.
I work at a service department so I know what you mean about servicing things that are "tweaked" and most people shy away. Warranty work is always tricky so I dont believe in trying to cheat the system. However, I think that people with chopped up wiring from poor stereo/alarm installs are just as bad. The only difference is that aftermarket superchargers/turbo's burn up O2 sensors instead of your windows randomly working or frying an odometer cluster (not joking here /hug Car Toys trainee).
The main boon of a turbo system is holding back the urge to turn up the boost. There is no such thing as free horsepower.
Once again, great feedback. Your all true professionals.
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