I did an engine a while back, swapping from Dougs to 1 3/4 hookers, peaks were about 4-5hp apart, 440ish HP 360. The hookers peak very similar to the tti step headers. The nice thing about the tti are they make good TQ down low.
The low end tq between Dougs and tti are pretty similar.
If the extra money tti cost is worth the gains to you, buy them.