I have a 2006 gs350, just installed invidia mufflers, am looking to instal mid pipe and cold air intake. Does anyone know the HO gains with these mods?

 

Mufflers will not do anything by themselves. Its a sound only mod. If you're changing mid pipe, but not changing the cat back to the mufflers or from the manifolds down, you gain nothing because you're choking the flow back down. A cold air intake is worth maybe 5 rwhp (anyone that claims more that, I'd ask to see some dyno charts).

Further more, without the ability to crack your ECU, your car will stay within stock A/F parameters.

So grand total....5 rwhp in good air.