How much power is bumping the timing really worth?

i wonder if the weight difference is the main reason for his being faster ...

in general, are the 99s heavier than the 95s?

is his a vert?

what computer/tune do you have?

wait till you get the windsor/s trim on there ....

a few thoughts on this one. i feel like there are way too many variables to pin this down, but here are my ideas:

1. increased weight vs. the 94/95 coupe
Reinhold Racing - Mustang weight information

2. are you positive about the gears on the 99? I'm assuming you checked the tag on the rear cover since I saw your build thread and clearly you have a good deal of mechanical experience.

3. does he have all accessories like a/c hooked up like you do? Or was he running a short belt?

4. did the owner perform any weight reduction in the 94/95 you are not aware of?

5. perhaps the eddy rpm intake is too much for the stock e7 heads - perhaps you are losing low end torque compared to the GT40 setup

6. not sure how many miles your longblock has vs. his, but that could be a possibility. i remember seeing an old article in MMFF or 5.0 magazine and a basic tune up on a 5.0 was worth quite a bit of HP when compared to the worn out parts

7. were you running around for a while with the a/c on prior to this run? i know my mercury feels like a dog with the a/c on and right after it's shut off on very hot days

8. computer/tune/sensor issues with the intake and a stock 94/95 tune. aka SN95 hell (and why I feel like so many people sell their SN5.0's after modifications)

i can't imagine bumping the timing would be more than 10 hp, tops, but i could be wrong. go for it! and like vert mentioned, wait til you get some BOOOOOOST and this will not be a problem!

the car looks great btw. cool swap and tasteful additions/removals (see ya side stripes!)

Ok here's a thought (that I would hate to be true), but on the rebuilt motor are they e7 heads? or are they older truck/crown vic heads?

some of the rebuilders in my area do some shady chit like that and sell them as "mustang engines"

again, cool swap. looking forward to the updates. I think you should throw boost at that longblock until it breaks like the old Tim Stockwell 5.0 builds (if you remember reading/seeing about those).
http://www.mustang50magazine.com/featuredvehicles/m5lp_0412_1992_ford_mustang_lx/index.html

My neighbor broke the ear off his Edelbrock Peformer intake and since I had an RPM upper sitting on my floor we put it on his stock motor so he could get to work / school. To both of us the car seemed much slower with the RPM. Seems to make power it needed to rev but we figured the heads / cam just couldn't handle the area where the RPM wanted to peak. He then took the Performer upper to welder where they fixed that ear. Went for a drive after installing the upper and the car had much more torque and usable power. I don't even think the gear you have is good for the RPM either. Although I can understand your putting a blower on. However the Performer intake even with a blower I believe will make more HP without over revving the stock heads / cam.