I can give you MY report...although it may be somewhat skewed as I did a cat-back at the same time. Anyway...

I have flutter but only between 2000-2200 rpm WHILE ACCELERATING. I do not have flutter at cruise.

Like "antelope V-10" I can now hold OD on grades that I couldn't before without either the TC unlocking or it dropping into Direct (3rd).

I lost no MPG. Not sure of any gains either as I do not really track my MPG on a regular basis. I AM tracking this tank and the previous tank simply because my tire pressures were down by 15psi. I upped them back to 52F/65R and want to see if anything changes. I also dropped in a K&N in a moment of weakness to (again) see if I could "feel" a difference. (I can't until around 4500rpm and then I'm moving too fast to care. I'm too worried about running off into a field of old lava! ) NO: I don't care about filtration. I change my oil enough.

The Flowmaster Y-pipe is worth the $40 + around $50 to weld on. I cannot attest to any custom or differing brands. But will say that most any is an improvement. Heck, I woulda rather had the unnecked down one that was on my 2000 Excursion!

I lost no low-end. In fact, I think mine is more responsive and low end actually improved. I can snap all my kid's heads back at a stop light (okay...that wasn't the best thing to say... I don't hurt them! Honest! ) ... where as before the intial stop light flooring was somewhat uneventful. Disclaimer: All my "inital stop light flooring" impressions are uneventful due to the fact that my motorcycle that I drive more often goes 0-60 in 3 seconds. I takes awhile for me to become acclimated to my truck(s). There is a definant difference, however.

I've been driving my truck all day today and have really been paying attention to it's power delivery as I wanted to post to this tonight. I put on about 150 iles today in a range of driving situations and can say that I am quite pleased with the final intake/exhaust mods. I WILL also say that I cannot wait to install 4.30s.

 

Definitely more power at low and top end. Check my gallery for install pics.