so first of all i want to clear up i am not matt but i am in the other forums. my 5.1 mustang was built by m&r about 6 months ago. the 347 was my buddies engine that we had m&r machine and balance then we put it together our selves though. i personally have had no problem with them and that is why i came on these forums to give them some positive feed back. The 5.1 modular motor was completely designed and built by them though. it makes a ton of power but it has alot done more than just a new low end. it has fully ported pi heads with a perfessional products port matched intake and comp cams and a ton of valve spring. when i tuned it we set the limiter at 7200 its a little over board for a street motor but i love it. so once again i am not matt just someone who uses and reccomends them.