No mate, you said "all LHB Coaches" which is completely wrong. If I recall correctly, Non-AC LHB coaches are probably not even tested above 145 kmph (IR uses 10% margin of safety, hence 145) because of air-resistance and poor ride quality.
AC LHB coaches are allowed upto 160 kmph, and Tejas with covered vestibules is allowed to clock above 160 kmph.