the one it is a good idea to do the other side to save money down the road... The cost is pretty high since the engine needs to come out! Hence the reason to replace or rebuild both turbos.. It cost me about $800 for both of my turbos to be rebuilt by Majestic( still have them if you need them) and an additional $1000 in labor for Nissan to put them in... I am sure u can find cheaper labor out there since Nissan was charging me $65/hr to work on my car... Let me know if you have any more questions... I have had a nightmare when it comes to turbos...