Just bought an SLX, had it out for the first time last week and was topping out at 54 according to the mfd. It had older looking plugs, but could that be causing me to lose almost 10mph from where I should be? I checked compression prior to buying, and got 132, 132, 123 from front to back. I was told that that compression is well within reason and would be fine. Any input would be great.