I am not made out of money, and dollars don't come easy for me, but my OPINION is this:
For the following reasons, I think the TTI's were worth every penny they cost me, and I'd do it again in a heartbeat, even if I had to rob a convenience store to get the money.... (I bought the headers along with the 2.5", H-pipe system. When I bought my setup, they didn't yet have the X-pipe, a better system, I think.)
1. Jewel-like construction, with beautiful welds and mandrel bends on everything.
2. Great-looking ceramic coating; looks like silver paint, but is a tough, durable, practical coating that is easy to care for.
3. Flawless fitment; engineered, and configured, to a gnat's eyebrow and cleared everything, with no interference, anywhere (my car's an automatic; I can't speak for the manual transmission cars.) Two-piece construction on the driver's side made installation a snap!
4. Thick, no-leak flanges, and the shape of them makes spark plug access VERY easy.
5. NO ground-clearance problems; no smashed-flat primary pipes... speed bumps are easily negotiated without incident!
6. Works equally well with screw-onto-the-block, OR 90-degree adapter oil filters.
7. "Stepped" design (1.625" primary into 1.75" pipes) deliver excellent horsepower for all but the largest stroker motors, and would work well on probably 90-percent of street-strip applications. A pure race motor would make more outright horsepower with bigger header pipes, for sure.
8. Aluminized exhaust pipes and tailpipes, for an attractive appearance and a long life, on the street.
All-in-all, probably the best money I have spent on my old barge... trouble free, and a joy to look at (and, listen to.) As I said, I'd do it again, in a heartbeat! These pipes are a long-term investment.
Just my 2-cents...