My one-year-old Suzuki Grand Vitara has just reached 13,000 miles. Full torque on this engine is at 1950rpm, but the RPM pick up is slow. Then it seems like a switch is thrown and the engine develops a rush of power. The dealer tells me this is normal, however I am not convinced. I have seen a simple plug and play device advertised, which is said to increase low rpm torque and bhp, while increasing fuel economy and also not adversely affecting the warranty. I would appreciate your comments.