Reliability will be down to the quality of the product and how well the product is fitted and how good the tune is, which is key.
Also good regular maintenance will go a long way to give you reasonable longevity.
Been there and done all the FI stuff, currently running an 810 bhp 350Z and a 900bhp R35.
Both these cars are predominantly used on track and both require super regular weekly maintenance.
You do not get a lot for 7K once you take into account the cost of supporting mods.