exhaust questions

I have a 2000 GT, but one of my friends with a 1990 LX 5.0 has some questions about exhaust. I helped him the best I could and figured you guyz know way more about this stuff than me so here are my questions.

How much is the power and sound differnce bettween Long tubes and shorties?
Is it worth the money you save to custome make an H-Pipe no cats. (I've always been told that the H-pipe sounds better on 5.0s)
If installing Long tubes do you have to lift the motor off the motor mounts (had to do that with my 4.6 for long tubes).
He is also thinking Flowmaster 40 series cat back.

This is mostly for sound not power. The headers will probly be BBK because of the price/quatitly you get with them. I've also had no problems with all the BBK products I've gotten thus far.

Thanks in advance for all the help.

well according to book time it only takes about 1.5 hours to do a 5.0 and 14ish for a 4.6. On my 4.6 I had to lift the motor about 8 inches off the motor mounts and then still rock the motor quite a bit. I'm hoping a 5.0 is easier. It is from what I've heard.

I did get the BBK long tubes and shorty x-pipe with my kit. I was mostly wondering about how hard it is to get long tubes on a 5.0 and the power differnces.

Thanks for the advice though. I'll let the guy know about the obvious power differnces. I figured it would be like the 4.6 in the long tube compared to the shortys but I had to make sure.