which would help the performance of my car the most.shortys or lt's?..its a 90 notchback 5.0 5spd...the car is mostly stock besides udps and ignition. i dont plan on changing the heads or intake anytime soon either..forgot to ask who makes the best fitting of both?..
None of the above... swap your stock H-pipe and be happy. The stock headers are more than capable of supporting the stock combo. New headers will show you little or no performance increase. Most likely, you'll just be pushing your bottom end torque a little higher into the RPM range.
The only real benefit I think that you would get from LTs is the sound. but other than that the stock headers will be fine. I would put the money into some other mods like gears or sfcs if you don't already have them.
I wouldn't say that LT's even benefit SOUND; my buddy hates his because when we had the exact same cat-back with O/R H-pipes and same motor setups, but his was only 1/2 as loud/deep as mine (and I just had OEM shorties). It seems that LT's will tend to change the exhaust NOTE slightly, but they also tend to reduce the VOLUME so much that the change is hardly even audible. That, and LT's are a pain to install; shorties are relatively easy to install (except for equal-length designs or GT-40P's), but they cost a lot for gaining practically nothing. You'd get, what, MAYBE 3-5 horses at best? Hardly seems worth $200+ and a lot of install time and headaches ... especially if you wind up snapping an exhaust bolt or two off in the process.
Invest in a set of pullies, and K&N panel filter, and a nice off-road H- or X-pipe and call it done - you can have all for the price of one average set of LT's or good shorties.
If i was doing a bolt on to a stock engine i would not go with LT at all. I would however swap out the stock shorties for a aftermarket brand and go with a high flow catted h-pipe or a off road h-pipe if you don't have emmissions testing. Upgrading the 2 1/4 inch exhaust to 2 1/2 inch is a great mod.
The stock headers are the best application for 5.0 motors! Up to about 250-260HPOnce you reach that mark its time to change headers. If the motors stock I wouldnt use an off rd mid pipe.Use high flow cats.Youll hang on to some of that low end torque that makes 5.0's famous!
I doubt yours is wierd. You are going to gain power by upgrading the exhaust systems on these cars. Anyone who says otherwises doesn't read many tech articles about the mustang. And i believe there have been a few written in the last 20 years.