that doesn't sound right. NYC already has enough yohimbine hcl and it is not necessary to add more. 4 NYC pills give you roughly 11mg of yohimbine hcl, which is quite enough.
plus you should be aware that too much yohimbine hcl can cause anxiety, irritability, increased heart rate etc.
maybe you read that people stack NYC with yohimburn, which does make sense, since one of them works for overall fatloss and the other for localized fatloss.