The reviews are pretty old. Recently purchased a exhaust from these guys. They responded via FB fairly quickly and picked up their phones immediately. They were helpful with making sure the part I am ordering actually fits the car.
If you are making purchases to your car you should be doing research prior to making the purchase. Dont expect them to give you advise on what brand or setup is good for you. Its all personal preference.
My experience was great. Jay gave me a exact day the shipment and was very transparent. Knowing it is the holiday season and shipments may delay, he gave me full heads up. Definitely would make a purchase from Jspec again.
Side note, they do installs but with a neighbour shop next door. Not sure how their services are.