Ive used rallydesign a few times, I just got my Group N spec Disc's and S/S Brake hoses from there. Good company.
I looked at the exhausts on there as well, I asume they are Group N spec simaliar to Ashley exhausts. Why not email them or phone them up and ask if it is a competion part, if it is its sure to performe well.
Don't be put off by the fact its not S/S, My janspeed system is Mild steel and is fine.
Theres been a lot of talk about OMP competion Exhausts as well over the last few weeks.