I assumed your orig question was with using oem parts 😞

My IS350 sound exactly the same. On the US forum some people have modded a sound proof cover off LSV8s to fit. Apparently only makes a small difference but noticeable.  

Yes, that’s normal is the sound associated with fuel injectors, if I’m not wrong. 

yes you can and im looking to do this, there are vids on youtube, not that hard at all, no mods needed just buy the parts, the conversions i have seen on youtube look awesome 

yes     Have one to sell? Sell it yourself   Shop with confidence   eBay Money Back Guarantee Get the item you ordered or get your money back. Learn more- eBay Money Back Guarantee - opens in new window or tab Seller information mars_performance (27417 ) 99.1% Positive feedback      Save this seller Contact seller Visit store See other items   F Sports Style Front Bumper bar & LED Lights & Grill for Lexus IS250 IS350 05-13    1 viewed per hour     Condition: Brand New   Compatibility: See compatible vehicles   Quantity: 5 available44 sold / See feedback     Price: AU $1,399.99   or 4 payments of AU $350.00 with Afterpay Buy It Now Add to cart Add to Watchlist   100% buyer satisfaction 44 sold More than 89% sold     Postage: AU $150.00 Standard Postage | See details     Item location: Clayton. VIC, Australia         Posts to: Australia See exclusions   Delivery: Estimated between Tue. 2 Feb. and Thu. 4 Feb.     Payments:      4 payments of AU $350.00 | Learn moreabout Afterpay - opens in a new window or tab   Returns: 30-day buyer pays return postage |  See details