Also make sure (If you order them) you just get the D453
http://www.summitracing.com/parts/DOU-D453/ These are coated.
D453R
http://www.summitracing.com/parts/DOU-D453-R/ Are RAW and need to be painted.
Also you lose very little power (doug vs TTI) The only time you would really want TTi (unless you just want to say "I have TTi Headers") is if your motor is pumping out a lot of horse power. At a 400 HP motor you might lose 3-5 horses between the two.
