my $.02...speaking as a guy who actually HAS applied forced induction to his 2.5L motor..
My vote, in this application goes for Single Turbo. In fact, in MOST applications.
Here's why...
Less heat...less complexity.
The subject of Lag has been brought up a bit. My answer? "Who cares?". Lag is GOOD for a FWD car...if I hit my 8psi at 1500 rpms, I'd be going thru tires left and right.
As is, with boost coming on ~2000 [How much lower do you want boost, anyway?] and maxing by 3000, my car spools soo fast traction is always a concern. Some of the things you can do to help (reduce) spool time is, use stock exhaust manifolds...MAYBE slight porting, but not much. Its all about heat and velocity to get that sucker moving....A little lag allows the car to get rolling. 1st gear is a joke. I need a much taller 1st gear.
Also mentioned was the "blow 8psi thru a straw!" etc. That is the argument that I used to take. But we are not pressurizing the piping, we are pressurizing a small paint jar at the end of the straw...in that jar, to pressurize it to 8psi (over atomospheric pressure), it would take the same amount of air volume, regardless of what is supplying the air (t25 or t88). The issue is, the larger blower will be working MUCH easier to do it.
Its mostly for that reason a single turbo will out-perform twins, in most applications....in order to keep the pressure up, the twins will be working much harder (read: hotter?) to provide similar gains. Not to mention, most turbos small enough to work would be way out of breath as you reach the top of the powerband.
now, for subjective remarks that I cant explain:
-Show me one of the Pro-Import guys using twin turbos?
-As mentioned before, show me one 700hp+ TT supra?
If a guy here wants to turbo his contour, use a well-designed SINGLE turbo set up. A single turbo set up will be cheaper, more simple, and out peform a tt set up in 9 out of 10 cases.
