I have an mp77 or at least used to. Anyways I compared it with my friend's mp100 and I noticed that although both racquets have the same length, the mp100 has a smaller head lengthwise, I don't know if this is normal, his mp100 could be fake. But if it isn't then this means that theoretically the mp100 has a smaller sweet spot but is more powerful due to the smaller head analogous to oval vs isometric heads.

What about the width?

If the width is slightly larger for MP100, it could because the string method. Especially for 4knots method, it's possible due to different machine (# of support) and different tension combination, the racket face becomes narrower or fatter than unstrung ones.

However, the above assumption only works if the difference is very small (less than 0.5 cm, maybe). If the difference is much more sig. than this, it's very possible that racket is a fake.

Ah yes, I forgot to mention that... The width is the same, I made sure of this because I also thought about what you said. I'd say the difference in the head length between the mp77 and the mp100 is about a centimeter to less than a centimeter. Also the other thing is that my friend managed to remove the sticker (apparently) that says UltimumTi on one side, I don't know how he did that, upon inspection of the the other side, I don't see how anyone could've peeled something that doesn't even look or feel like a separate layer from the shaft.

i've never mention it before but yes, the mp 100 & 99 string bed area is smaller than other isometric with iso900/TiSP having the largest string bed area.

the MP100 and MP77 are completely different beast. look at the following thread:

http://www.badmintonforum.com/vb/showthread.php?s=&threadid=3555&highlight=mp100+mp77