Totally agree with you on claims made by aftermarket parts suppliers.  Would be nice to see some documented testing.

As to your comment about Toyota engineers - keep in mind they were constrained by many things that are often not relevant, or at least not as important to enthusiasts building these engines 30 years later.  If you want significantly more power than stock you pretty much *have* to go with aftermarket parts, especially headers, cams, and carbs.

Emissions were a huge deal for them, along with cold starting, low speed drivability, durability, economy, and manufacturing costs.  I know guys in Cali. have to worry about emissions, but a lot of folks in other places, like here in WA, don't.  I can put whatever I want in my truck and the gubmint doesn't care.  I also don't care a whole lot about cold starting, I know how to get a performance engine started and how to deal with it for the 5 minutes it takes to warm up.  I'm also not expecting this engine to last another 220K miles like the stock one did, nor am I concerned with saving $0.50 on each valvespring because I'm not installing millions of them.

That said, it seem like any time you start dealing with aftermarket parts and deviating from stock things often don't fit or work right without some serious dicking around...