How high is it really possible to push them? I'm thinking 12 on a human, but beyond that I'm out of ideas. I know trolls can get 18, give or take a little, as a stat max for say, strength. About the most I can concieve for the non-goblin races is a 13/12 elf, for Agi/rea, with metagenetic improvements, genetic optimization and exceptional attribute

A Fomori ghoul can have up to 22 augmented body, along with 12 reaction and 19 strength. (No genetic fiddling allowed, though)

Humans can roll around with an effective Strength 15 if they use the +3 Str mod to military grade armor (which is specifically exempt from the stat max). Hauling out a 9P throwing knife for a stealth kill is kind of ridiculous, but fun

I rolled an ork ghoul with 19 strength (on his arms) while wearing his Ruthenium-coated milspec with Thermal Damping. Fun times with a combat axe and a longbow dealing damage comparable to an assault cannon without the noise.

Double postery.

In the Shadowrun Missions forum, I posted a hypothetical max starting dice pool. I'm on an iPhone, so I can't copy/paste, but from memory...
Attribute 6
skill 6
extraordinary attribute 1
geneware optimization 1
surge 1
race 0-4
so 15-19 x2 is the cap for how big your dice pool is allowed to be with all the positive modifiers you can think of.

It was something like 135 BP - you can see all the math in that thread.