There is just no way that putting LT’s with no tune on is going to be dangerous. What do stock GT’s make at the rear wheels? 275hp? And I know there have been claims of 25hp with long tubes but I don’t buy it, especially with what is, for all intents ad purposes a “stock” motor. I’m thinking 18hp MAX. That’s about a 7%hp increase. But just for fun, and to shout up some of the whiners lets call it a 10%hp increase. Now lets say that Ford has their stock tune dialed right in perfect (for making max hp/tq) for a NA motor which is about 13:1. But I have never seen an OEM car make anywhere near that. They are usually down in the 12.5:1 range (a bit fat for bad choices in fuel, etc). So now you take that 12.5:1 motor, throw some headers at it that gain at MAX 18hp (a 7% increase) and what do you theoretically get? You get a motor that will be 7% leaner. That’s only .875:1 leaner than stock for a A/F ratio of 13.375:1, which is still safe by MILES (actually it’s just about ideal for a high performance motor with aluminum heads ad block).
Of course all the above calculations are rough and don’t take into account the billions of variables that make up a true ruing A/F ratio. But they are going to be close. And an A/F ratio of 13.375:1 is nowhere near dangerous. You could add a whole point more and it would still be under schizometric (14.7:1) which is not ideal for maximum power, but certainly safe. And in addition to that it’s not like you get to 15.7:1 and the motor melts down. It would just be lean, run hotter than it should be and not put out much power. But permanent engine damage, no way.
Yes, it would be ideal to tune for the headers. But we are talking about a super lazy, mass production V8 that was designed for the lowest common denominator and all the stupid crap that it could be subjected too. Compared to a “built to the max” 3v the stock motors are incredibly safe. How safe? Well I just rammed enough air into mine to increase the HP 72% without removing a valve cover. I think it’s fair to say that the stock motors are pretty stout.