jerstilly
I agree most folks prefer the long tubes. You get more hp on the top of the rpm curve.
However, you have to be willing to spend $700+ to get quality headers like Stainless Works or American Racing headers or JBA's. Also if your state does emissions testing the LT wont pass.
Also the tune is the key to making the LT hp. Some folks have put them on and ended up only making 7-8 hp.
I just ordered the JBA 1 5/8" equal length shortys today from LMR for 479.95 with free shipping for my 05 Mustang.
From the info out there you can expect 10 - 12 hp gain. The JBA web site has dyno results on a 2005 Mustang with a Steeda CAI & SCT tune - UDP - JBA Axel back and the JBA shorty. The stock average hp was 220 and torque was 262. Then with the headers it went to average 237 hp and 283 torque. Difference ia 17hp and 21lbs of torque. I've also seen JBA advertise 20 hp gains on the equal length shortys.
I'll be scheduling a mustang chassis dyno soon after I get them installed. I will post the results. Bottom line you can loose some weight over the OEM headers as well as a min of 5 hp gain, and still be emissions legal.
Thanks, Dewman