Re: just got an 89 5.0 lx
don't run without a tstat.. 1) the blockage in the system has a cooling effect (think like the fixed orifice in your AC system) and 2) if a car runs cooler than 160* cylinder wall wear is something like 5-10x what it is at optimum operating temperature when the entire engine is expanded and running as designed..
as far as modifications..
with 3.73 gears, a short throw shifter, CAI and exhaust (seems you already have exhaust) I ran high 13s with my 5.0..
2012 IS F Blue IS F Sport
2006 Mustang V6 wannabe