Or even more.

Minimum for a K&N filter nowadays is 3.5k - 4.5k (might be 4k minimum by now).

After that, mandrel bent headers start from 10-20k (20k should be stainless)... then you have to do the midpipe with a good resonator. Problem with local resonators is the question of good flow (kung di makinis ang loob), with secondhand resonators or mufflers, if they have fine mesh interiors, these can become delaminated or un-welded over time and start to rattle.