I own a 1990 Gt convertible and i want to upgrade my exhaust. I already have stock manifolds, 3" o/r H pipe, and flowmaster catback. I was thinking of getting side exhaust but i cant find a kit for 87- 93 Mustangs. I was thinking about a custom kit, but my question is, will it cost me horsepower to go out the sides. I am trying to choose between side kit or slp catback. Also does anybody know how good of quality the BBK shorty headers are? They seem to be the best bang for the buck. I hope somebody has some oppinions for me.
Thanks
JEFF  

I use the BBK shorty headers on one of my stangs and they are great! Long tubes will give you a broader torque curve, but, are more exspensive. I also have experimented with the side exhaust. In naturally aspirated form I lost 2 tenths in the quarter. I picked them back up when I went back with the flowmaster after cat system. 3" is a little arge for a stock or mildly modified stang. I would go for at least 1 5/8 primaries.  

bbk shorties are a nice product, but a 3" exhaust on a non-modified motor is actually bad for performance. i agree with "samk" on the 1 5/8" primaries. i think steeda makes a decent side-exit exhaust for foxes, though i don't see why you would lose h.p. with such a system.  

my setup is bbk long tubes, shorty x-pipe no cats which I have on a 91 5.0 and a 00 GT.  I figure spend the money right away and get the most power.  The shortys arn't a bad choice because they don't loosen up as quick, but I've always loved the sound of long tubes.
Like everyone else has said " 3 inch is just overkill."  I found a Magnaflow system for your body style for a desent price in JEGs Performance.  Side exhaust will always cut down power because the exahuast goes in and comes out of the same side.  Also keep in mind that if you go with side pipes you will not beable to add subframes in the future.  

my setup is bbk long tubes, shorty x-pipe no cats which I have on a 91 5.0 and a 00 GT.  I figure spend the money right away and get the most power.  The shortys arn't a bad choice because they don't loosen up as quick, but I've always loved the sound of long tubes.
Like everyone else has said " 3 inch is just overkill."  I found a Magnaflow system for your body style for a desent price in JEGs Performance.  Side exhaust will always cut down power because the exahuast goes in and comes out of the same side.  Also keep in mind that if you go with side pipes you will not beable to add subframes in the future.  

Well I went with the bbk long tubes and the short o/r H-pipe. I have not installed them yet but I ordered the SLP Loudmouth system and installed it, I am very pleased with this one. I cant wait to get on the headers but my next question is, after I install all this, should I take the thing to get it tuned?  

would not be worth it.  All your doing is letting your car breath.
You could if you want acouple extra horse.  

Well now i drove it a couple days ago after i installed the long tubes. It seemed to want to shut off on me when i got off the clutch to gas like it lost power then i would have to give it more gas. Then i cracked into it from 2nd and there was no power just a loud pop. then i got into it from first and it felt great. I dont know if this could be a fuel problem or what, but maybe its just because it was really cold outside. also ever since i have had the car i have to restart it about 4 times before it will stay running. If anyone has any imput it would be appreciated. thanks  

Check all your plugs and plug wires.  I put a set of larger headers on '94 and it immediatly heated up the boot and exposed a crack on an older set of wires.  The crack allowed it to short on the header and with the one cylinder semi firing the car stumbled and popped untill I found the offending wire (i.e. started it in the dark and looked for the spark)