whats the longest stud I can safely put in my rx-1's ripsaw?

[shanksRX-1]

Whats the longest stud I can put in my 05 rx-1 safely??? Im ordering the same track thats on it stock. Its a 1.25"lug ripsaw. I am putting 144 down the middle. I want to hook up good and I dont really want to go with 192 so I want the most penetration I can get.
Oh ya and do I need to order tunnel protectors. With all my xc's They came with the heat exchangers setup so they acted as tunnel protectors and you didnt need to put them on but IDK with this new yamaha

Thanks guys!!

 

[local 25]

1.325 i believe...

 

[newrx1guy]

I have 1.375 in my 03 rx1 with 1 1/4 ripsaw. I have 96 down the center