I have a 2002 Bonneville SSEi with a 154,000 miles that I just bought and I want to upgrade it's hp to about 300. Any suggestions????

Check out Intense Racing and ZZPerformance. Those are the two main sources for aftermarket parts for us. I tend to lean more towards Intense whenever possible. Myself and many others have had miscellaneous issues with ZZP. Unfortunately for some items ZZP is the only one that carries the product.

The typical starting point would be Intake, Headers (Search for Speed Daddy Headers on eBay), supercharger pully etc. You will want to get a scanner to be able to scan for KR. You'll be looking at probably upgrading the supercharger to a Gen V (from 2004+ Grand Prix) or porting your Gen III, a cam and/or rockers and intercooler as well to get close to your 300 number.

The big ticket item here is going to be the transmission. Triple Edge Performance is the go to for the 4T65's.



But for example my mod list is in my signature below, and I dyno'd 253whp / 354ft.lb. before the 1.9 Rocker install.

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'93 SSE "Guinevere" RIP 1993 - 2019
'01 SSEi "Chloe" Mods: Intense FWI | GenV | WBS Intercooled | 3.2 MPS | 1.9 YT Rockers | SSAC Headers | N* TB | TEP Trans | 3.29 FDR | Torsen LSD
DTM Tuned | Dual AeroForce | Solid Mounts | 255 Walbro Pump | Fuel Logs | GXP STB & Sway Bars | CSS Lowering Springs | GXP Brakes | Disabled DRL
Magnaflow Mufflers | Magnaflow Cat | GXP Seats & Trim | 35 % Tint | Cleared & Tinted Tails | repinS Retrofited Morimoto Mini H1 | 19" GT500 Wheels
'09 G8 GT "Abigail" Mods: Rotofab | LS3 Heads, Intake & Cam | Kooks LT | Solo Exhaust | Tien Springs w/ GXP Struts | Whiteline Swaybars | BMR Subframe Connectors
Achievements: Guinevere - 264k mi | 16.27 @ 84.10mph | March '11 COTM :: Chloe - 223k mi | 13.85 @ 102mph | January '09 COTM :: Abigail - 192k mi | 12.85 @ 112mph