My old koni coilovers are shot. Looking for an affordable option with reasonable spring rates for aggressive street driving with around 400 rwhp. Anyone have experience with the TEIN Street Advanced coilovers? On paper, they seem to meet my goals.

 

I would step it up to the Flex Z that come with upper mounts, the Street Advance reuse the OEM rubber mounts, if yours are shot it will cost you another $400ish.

 

Yep, as Banzai Racing said.
I was in the same boat... was looking at the streets but decided to get the Flex Z.
They are a nice budget friendly coilover.