"Let me say, I believe this will work best on index Specially these parameters are suited to S&P index"
My young cousin believes in Santa and the Boogie Man.
Whether you believe your method will work best on an index is irrelevant.
From a research point of view, you should be stating your arguments as to why you think your strategy would work best on an index.
By doing so, other readers can get a better understanding of your thought process and provide objective opinions, or other advice regarding your process. This is a critical component of formal research (and a very good idea for informal research as well).
If you simply say "I believe in ....", that's a relatively subjective remark, and you can't get much useful feedback from such a statement.
However, if you say "Index XYZ has the following characteristics...my method can exploit those charactersistics...therefore, my method will work best on index XYZ" is a more concrete example. It shows more of your thought process, and other readers may be able to provide other information to help prove/disprove your theory.
Regards,
Brandon