I had the turboXS Type RFLs and they were very very loud. They were probably the loudest ones out there, but if you reved the engine up really high and let off, the car would stall. No matter how many washers I put in there, they still did that. I put some HKS Bovs on there and it didn't do that anymore. HKS Bovs are alot better quality and very loud at the same time. I personally like the sound the HKS make more than the Turbo XS ones. This is just my 2 cents on them.